Game Design in Virtual Reality

DIPLOMARBEIT

zur Erlangung des akademischen Grades

Diplom-Ingenieur

im Rahmen des Studiums

Media- and Human-Centered Computing

eingereicht von

BSc. Onur Gürcay Matrikelnummer 00827880

an der Fakultät für Informatik der Technischen Universität Wien

Betreuung: Ao.Univ.Prof.Mag. Dr.Horst Eidenberger

Wien, 1. Jänner 2021 Onur Gürcay Horst Eidenberger

Technische UniversitätWien A-1040 Wien Karlsplatz 13 Tel. +43-1-58801-0 www.tuwien.at

Game Design in Virtual Reality

DIPLOMA THESIS

submitted in partial fulﬁllmentofthe requirements forthe degree of

Diplom-Ingenieur

Media- and Human-Centered Computing

BSc. Onur Gürcay Registration Number 00827880

to the Faculty of Informatics at the TU Wien

Advisor: Ao.Univ.Prof.Mag. Dr.Horst Eidenberger

Vienna, 1st January, 2021 Onur Gürcay Horst Eidenberger

Technische UniversitätWien A-1040 Wien Karlsplatz 13 Tel. +43-1-58801-0 www.tuwien.at

Erklärung zur Verfassungder Arbeit

BSc. Onur Gürcay

Hiermit erkläre ich, dass ichdieseArbeit selbständig verfasst habe,dass ichdie verwen- detenQuellenund Hilfsmittel vollständig angegeben habeund dass ichdie Stellen der Arbeit–einschließlichTabellen,Karten undAbbildungen –, dieanderen Werken oder dem Internet im Wortlaut oder demSinn nach entnommensind, aufjeden Fall unter Angabeder Quelleals Entlehnung kenntlich gemacht habe.

Wien, 1. Jänner 2021 Onur Gürcay

Acknowledgements

First of all,Iwouldliketothank Prof. Eidenbergerfor supporting me through my years at TU Wien and helping me restore my self-conﬁdence.

Iwouldalso liketothank AhmedOthman whoalsoworked on theVreeclimberprojectand prepared the template everyone is currentlyusing for theirvirtualclimbing applications. He alwaystried to make timewhenever Ineeded someone’shelpduring the development and evaluation stages of thethesis.

Ialso want to thank my sister,BurcuGürcay-Morris, who has alwaysbeen therefor me and ready to helpnomatter what.

And lastly, Iwanttothank my test groupfor making time for me in thecurrentstate of the world.

vii

Kurzfassung

Das letzte Jahrzehnthat sehr große Verbesserungen in derVirtuelle Realität (VR)- Technologiegezeigt.Neben Gamingwird VR in vielen unterschiedlichen Bereichen wie im medizinischenBereich verwendet. BeispielsweisekönnenChirurgen lernen, kompli- zierte Operationen mehrmals in VR durchzuführen, ohnedas Leben ihrerPatienten zu riskieren. Die Möglichkeiten wie in diesem Beispiel erweiterten die Anwendungsbereiche bedeutend, als der führende Sektor, Gaming,für die Verbraucher attraktiverwurde. Viele Spieleentwicklungsunternehmen begannen,immersiveErlebnissezuproduzieren, welches zu derStärkung ihrerPositionauf dem Markt durchdie Gewinnungneuer Benutzer führte.Trotzall dieser Entwicklungen bleibt VR-Gaming jedoch immer noch hinter dem traditionellen Videospielerlebnis zurück, hauptsächlichaufgrunddes Mangels an hochwertigen Inhaltenund der zusätzlichenKosten, die mit VR-Geräten einhergehen. Der Hauptgrund fürdie Knappheit an hochwertigen Inhalten ist, dass das Erstellen von VR-Spielen immernochdas Ausprobieren neuerIdeen erfordert, in dem das allgemeine Wissen über Spieldesignverwendetwird, dasaus der Entwicklungvon Videospielen stammt. DieTatsache,dass derSpieler in VR-Spielen präsent ist, sollte die Perspekti- ve der SpieledesignerbeimAufbau derErfahrung ändern.Die Spieledesigner müssen Spieldesign-Elementewie Ästhetik,Herausforderungen und Wiederspielbarkeit anpassen und so ändern,dass dieVRfür die Spieler immer noch überzeugend sein kann.Um diese inhaltlichen Probleme anzugehen, untersucht diese Diplomarbeit die Anwendbarkeit verschiedener digitaler Spieldesignelemente auf VR-Spieledurch die Entwicklungeines VR-SpielsnamensAstroclimb. Astroclimbist ein Science-Fiction- und Weltraumspiel, beidem es darum geht, eine Himmelswand im Weltraum hochzuklettern.Der Kletterteil des Spiels ﬁndet dank des Vreeclimber-Projekts derTUWien auchinder Realität statt, einemVR-Klettersystem, daseine unendlichrollende Kletterwand ermöglicht.

Während der Entwicklungsphasevon Astroclimbwarendie Verbesserungen der Qualität der Benutzererfahrungund des ErmöglichenseinerhohenImmersion-Stufedie Hauptziele vonAstroclimb. Dieendgültige Versiondes Spielswurdevon einerkleinen Testgruppe mit Fragebögen und optional kurzen unstrukturiertenInterviews sowie die Beobachtung des Spielers während des Durchspielens evaluiert. DieAuswertung zeigte,dass dieAnwendung verschiedener Spieldesign-Elementeerfolgreichdie ImmersionimSpiel steigerte und das Spielfür die Spielerattraktiver machte.

Abstract

The lastdecade showedimmenseimprovements in Virtual Reality(VR) technology.VR is usedinmanydifferentareasother than gaming suchasinthe medical area. As an example, surgeons can learn howtoperformcertaincomplicated surgeriesoverand over in VR without risking anyone’slife.The possibilities suchasthis example widenedits application areas significantlyasthe leading sector, gaming, became moreappealing to consumers.Manygame developmentcompanies started to produce immersiveexperiences which ledtostrengtheningtheir position on themarket by attracting newusers. However, VR gaming stillfalls behind the traditionalvideogaming experience mainly due to the lackofqualitycontent andthe additional coststhatcome with VR devices. The main reasonbehind the scarcityofqualitycontent is that creatingVRgames stillinvolves trying out new ideas by using the general knowledge of game design inheritedfrom developing videogames. The factthatthe playerispresentinside VR games should change theperspectiveofthe game designers while building the experience.They needto adapt gamedesignelements such as aesthetics, challenge,and replayabilityand change them in suchaway so theVRcan be stillcompelling to players. To addressthese content-related issues, this thesisinvestigates theapplicability of differentdigitalgame design elementsontoVRgames by developing aVRgame called Astroclimb. Astroclimb is ascience fiction and space-themed game that revolvesaround climbing acelestialwall in outer space.The climbing part of thegame alsotakes place in realitythanks to the Vreeclimber projectofTUWien, whichisavirtualrealityclimbing system thatenables an infinitelyrollingclimbing wall.

Duringthe developmentstageofAstroclimb, improving the qualityofuser experience and thelevel of immersion were the two main goals for Astroclimb. The ﬁnal versionof the game wasevaluated by asmalltestgroup with questionnairesand optional short unstructuredinterviews as well as observing the playerduring the playthroughs.The evaluation showedthatthe application of diﬀerentgame design elements successfully increased the immersion level in the game and made thegame morecompelling to players.

Contents

Kurzfassung ix

Abstract xi

Contents xiii

1Introduction1 1.1 Problem Statementand Motivation ...... 1 1.2 Aim of theWork ...... 2 1.3 Methodological Approach...... 3 1.4 Thesis Structure ...... 4

2State-of-the-Art 7 2.1 Virtual Reality...... 7 2.1.1EvolutionofVirtualRealityoverthe Last Decade...... 7 2.1.2Application Areas ...... 9 2.1.3Interaction Techniques ...... 12 2.1.4VRGame Development...... 15 2.1.5Game Releases ...... 17 2.2 GameDesign ...... 19 2.2.1Deﬁnition of Game...... 19 2.2.2DigitalGame Design Elements ...... 21 2.2.3Game Mechanics ...... 24 2.2.4Playtesting ...... 25 2.2.5Reﬂection on Virtual Reality...... 27 2.2.6Immersion ...... 29 2.2.7Motion Sickness ...... 31 2.3 Climbing in Virtual Reality...... 32 2.3.1TraditionalIndoor Climbing ...... 32 2.3.2VirtualClimbing ...... 33 2.3.3VirtualClimbing Technologies ...... 35 2.4 Related Work ...... 37

3Conception of Astroclimb41

xiii 3.1 Requirements forDesigning theGame...... 41 3.2 Design Approach...... 42 3.3 IncludedGame Design Elements ...... 44 3.4 Possibilities for Improvement...... 46

4Implementation of Astroclimb49 4.1 Overview ...... 49 4.2 Created Scenes in theGame ...... 49 4.2.1The Moon Scene...... 49 4.2.2The Owl Scene ...... 51 4.2.3The Asteroid BeltScene ...... 52 4.3 Gameplay and Atmosphere in theGame ...... 55 4.3.1Game Chapters and Events ...... 55 4.3.2Score, Timer,and HeightIndicators ...... 56 4.3.3Modelingand Use of Game-ready Assets ...... 57 4.3.4Music and Sound Eﬀects...... 59 4.4 TechnicalAspects...... 61 4.4.1Calibration Process ...... 61 4.4.2Scripts...... 62

5Evaluation 65 5.1 Setup...... 65 5.2 Covid-19 measures ...... 69 5.3 Testing...... 69 5.4 Results ...... 70 5.4.1Immersion, Aesthetics,and Story ...... 70 5.4.2Fun, Tiredness, and Motion Sickness ...... 72 5.4.3Problem Solving,CriticalThinking, and Replayability..... 74 5.4.4Element of Surprise, Curiosity,and Progression ...... 75 5.4.5Overall Results of Applying GameDesign Element...... 77 5.5 Discussion ...... 79

6Conclusion and Future Work 81

AStep-by-step Test Procedure 83

ListofFigures85

Bibliography 87 CHAPTER 1

Introduction

1.1 Problem Statement andMotivation

Thisdiploma thesis focuses on applyingtraditional gamedesign elements used forvideo games to virtual realitygames withoutmaking anyconcessions to themost important aspect of virtualreality “immersion”[97]and improving it if possible. Virtual reality is stillafairly new technology.Game developmentinthis areahas not gained thepopularity of PC, console,ormobile gaming yet. There are several reasonsfor this unpopularity which can be divided intohardware and software-related problems. Oneofthe main hardware-related issues is the priceofthe device and theadditionalcostsitbringswith itself.Apart fromthe pricedrawbacks,virtualrealitydevicesare still clunky to use and discourage userstoeventry them out.Technology still needstime to improve the hardware and increase theusability of virtual reality devices.

Software-related issues are mainlycontent-basedbecause peopledonot want to payfor a relatively expensivedeviceifthe amountofthe game content they willreceive with it is lacking or not as high quality as on PC or console platforms. These reasonsand many morehave been causing adeficiency of consumerattractiontovirtualreality compared to PC,console andmobile gamingwhichdid nothelp with shapingthe necessary game design propertiesfor virtual reality. To shadealightonthe content-related problems and define possiblegame design principles for virtualreality, the diploma thesis investigates the followingresearch questions: • Are common and generallyacceptedgame design practices and methods directly applicabletothe virtualrealityplatform?Inwhat waydocoreconceptsofdigital game design suchasimmersion,usability, andgame feelmean differentlywhen applied to the virtual realityexperience?

• At what levelcan problemsolving, critical thinking, elementsofsurprise and

1 1. Introduction

suspense, physical training and activity, engagement, and competition be applied while designing agame for virtualrealityplatformstoincrease the qualityofuser experience without anynegative side-eﬀectsfor virtual reality? The thesis exploresthe mentionedpointsinorder to make virtualrealitygame design more appealing and enjoyable to users withoutcausingany disadvantages suchasdecreasing the immersionorbolsteringcybersickness thatcomes withit.

1.2 Aim of the Work

The thesis aimstodesign agame for theongoing virtualrealityprojectcalled Vreeclimber [35]. Vreeclimber’s infrastructure consistsofavertically rolling climbing system that enables theclimbertoexperience the sensationsofclimbing in aperfectly safe environment. Sincethe mechanical and logical aspectsofthe projectare ﬁnalized,itopened up opportunities to createcontent for the project. Thecontent of thegame is based on a playground in adeep space where theplayerhas themissiontoclimbacelestial wall. The pure reason behind this choice is providingplayers with an environmentthat would givethemaunique experience.

Vreeclimber’s templateproject comes with algorithms that enable climbing in virtual realityvia acalibration process. Thecalibration process initially detects the trackers on the wall to align thephysical wall and theclimbing holds with theirvirtualrepresentation in the virtualenvironment. In addition to theinitialcalibrationprocess, the climbing holds remainaligned during the rotationofthe wall. Avatar hands and shoes used in the virtualenvironmentare the second part of thecalibrationprocess,enabling players to track their hands and feet accordingly.

The implementation of thegame aimstoinclude various game design elements which should make sense with the plannedgameplay forthe game. The ﬁrst gameplayideas thatwereconsideredare listed below:

Diﬃcultylevels The diﬃcultylevel of theclimbing can be adjusted by rendering out acertainnumberofavailable climbing holds which leavesthe climberwith asmallerpool of climbing holds to choose from during theclimb. Thesmallerthe number of climbing holds themore challengingthe climbbecomes.

Sandboxmode Thismoderepresents no winning or losingasthe term “sandbox” states. However, ascoringsystem canbedeﬁnedfor using speciﬁctypes of grips during the climb. Grasping those grips would yield ahigherscoreinthe end.Competition elementscan be added by creatingaglobal scoreboard or theclimbers cansimply try to beat theirpersonal bests.

Transitionsbetween scenes The look of thevirtualenvironmentcan be changed basedonthe progression playersmade throughout the game.

2 1.3. Methodological Approach

The implementation is mainlybaseduponthese gameplayideas with some modiﬁcations and adaptations to thegame design elements. During thegame design and implementation processes, the diﬀerences between designingavideo game and avirtualrealitygame should be considered in order to takeadvantage of thevirtualrealityaspect.The applied game design elementsshould furthermore be in harmonywith each other to increase the qualityofuser experience without lowering the immersion levels. The prototypes should be created followingthese points.

After eachgame prototype, thefunctionalityand theeﬀectsofthe addedgame design elementsshould be tested. Based on thegiven feedback, the appropriate parts of thegame should be adjusted to meetthe requirements and improvethe overall userexperience. After thecreationofasatisfactoryprototype, atest group correspondingtothe scopeof athesis should be usedtoevaluate the successrateofthe usedgame design elements, their impact on thequalityofuser experienceand immersion.

1.3Methodological Approach

The methodological approachcompromises of thefollowing steps:

1. Literature Review: Firstly,researchonthe definitionof“game design”and its elementsisdone while investigatinghow theychanged overthe years with the advancements in technology and if virtual realityplayedaroleinthese alterations. Thispart of theresearchwas important to understand the influenceofvirtual realityongame design.Since there wasnot asingle setofgame design elements thatare accepted globally,along list of differentgame design elements and their sub-elements wascreated.The next stepwas narrowingthe list down by eliminating the ones that are not compatible to virtualreality.The elimination happened per definitionand choicesince it is impossible to includeevery single game design element that is mentioned in the literature. The result of this part of theresearch wasanew categorization of game design elementsthatare commonly accepted and game design elementsspecific to virtual realitygames.Anotherpart of the researchwas determiningthe advantages and disadvantages virtual realitybrings to the table while designing games. Thegathered information helped with filtering the game design elementsfurther. In addition to thesefindings, furtherresearch on theeffectsofusing chosen game design elements on theplayers helped improve the userexperience.Furthermore,itimprovedformingdirectives to come up with bettergame-playideas.

2. Implementation: The implementation of thegame prototypewas performed by using Unity game enginewith the helpofSteamvirtualrealitysoftware forvirtual realitycapabilities.Previously mentioned game-play ideaswerethe starting point forthe implementation part. Sincethe center pointofthe game is climbing a physical climbing wall with supporting virtualrepresentations, some of theused assets were pre-deﬁnedsuchasthe virtualclimbing wall and avatar hands. They

3 1. Introduction

were amust-have to achievesimple climbing in avirtualrealityenvironment. The composition of theobjects in the virtualenvironmentwas created by modeling and using game-readyassets. Adding game design elementstothe game started with creatingthe environmentand continued with implementing the gameplay. Somegame componentswere modiﬁedorremovedthroughout the implementation process to meet the requirements and provideplayers with abetter experience. Furthermore, the calibration process received some adjustments to meetthe game- playrequirements.During the whole implementation process themost important aspect of virtual reality, immersion,iskept in mind so theideasoradded game components do not break it.

3. Playtesting: Duringthe whole implementation process, everyadded feature was testedand feedback wasgiven based on theexperience fromthe test sessions. The testingsessionsand receivedfeedbackhelpedwithimproving the weak points of the game. Moreover, playtesting alsoprovedand disprovedsome ideas that sounded reasonable during the brainstorming process.

4. Evaluation: The evaluation process consisted of diﬀerentmethods to gather data fromthe participants. The initial methodwas using aquestionnaire to gather information aboutparticipants’gaming and climbing habitsand experiencesbefore the climb. Theparticipants were furtherencouraged to thinkaloud duringtheir game sessions. Asecondquestionnaire washanded over to the participantsafter theirexperience with Astroclimbtogain insightintotheirexperience regardingthe immersion level they perceived,the impact of using diﬀerentgame design elements, and quality of user experience.Moreover, ashort unstructuredinterviewwas conducted afterwardstoreceive further feedbacktoimprovethe game and user experience.

1.4Thesis Structure

The second chapter of thethesis presents the currentstate-of-the-art. The section starts with givingsome information about theevolutionofvirtualreality over the last decade, virtualrealityapplicationareas, and itspossibleinteraction techniques.Itthen explains the stages developing agame goes through. The subsection alsoincludessome virtual realitygame examples on themarket and theircomparison with eachother. The game design subsectioncovers the definitionof“game” which givesinsight into game design elements. It alsoexplains what game mechanicsmean for agame and howplaytesting is acrucial part of thegame design life-cycle. All theseaspectsare then reflectedinvirtual reality. It further clarifies theadvantagesand disadvantagesvirtualreality brings. The importanceofimmersion in virtual realityand motionsickness covers the next subsections. Moreover, climbing in virtualrealityand the tools that enablethis experience formsthe last sections together with the related work done in the researcharea.

4 1.4. Thesis Structure

The thirdchapter covers the conceptionofthe game. The first subsection explainsthe researchquestions and requirements thatare necessary to create aspecific concept of the game. The design approachcoversthe ideas behind designing the game and whythis approachischosenbasedongiven tools to work with.The sectionalso informs about the chosen game design elementsand theireffectsinthe game. Lastly,the possibilities to improve the game are discussed.

The fourthchapter includesall relevant aspects of technically designing Astroclimbwhile the ﬁfth chapter reﬂectsresults from theevaluation. Thelast chapter gives ashort summary of thewhole work done forthe thesis and possiblefuture work thatcan be achieved with theproject Vreeclimber.

CHAPTER 2

State-of-the-Art

2.1 Virtual Reality

2.1.1EvolutionofVirtualRealityoverthe Last Decade Virtual realityhas been aroundfor decades,however, it has only recently started to gain momentum due to advancements in science and technology.Theseimprovements brought the currentstate of virtual realitytoapointthatmade it look far diﬀerentthanhow it started with Sutherland’s “The UltimateDisplay" [26]. Howweviewand usevirtual realitychanged overthe decades with theimpactsofmultiplebreakthroughs in research and innovation.

One of thesebreakthroughs happened withGoogle introducingStreetView in 2007 [53]. Street Viewisavirtualrepresentation of our surroundings all overthe world thatis supported by Google Maps[52]. It consists of millions of panoramicimages that enable people to virtually explore the world. Google,then releasedavirtualrealityversion of Google Earth [51]for Valve’s Steamcomputergaming platformand integrated Street ViewintoGoogleEarthVR. Thisupdateletsthe userexplore Street View imagery from 85 countries right withinEarthVRbyusing VR controllers [79]. Figure 2.1 shows auser usinganHTC VIVE headset with itscontrollers to navigatethroughthe world.

Anothercrucial breakthrough for VR wasthe design of theﬁrst Oculus Rift VR headset prototypein2010 [83]. Palmer Luckey,the inventor of theOculus RiftVRheadset, kickstarted his design in 2012 for enthusiasts to backhis project. John Carmack’s [109] shortdemonstration of an early versionofthe prototypeatthe E3 event[33]helped Luckeyreceivemore than enough endorsements to reachhis goal. Figure2.2 shows howthe very ﬁrst prototypewas assembled forits display at theexpo. The modest campaign goal of $250,000 broke2milliondollars in ashorttime with the generous help of knowngaming industry namessuchasJohn Carmack, and GabeNewellofValve

7 2. State-of-the-Art

Figure 2.1: With the helpofthe controller theuser is abletoselectalocationonthe smallglobeand ﬂy towards it. [56]

[77]. Aweek before Facebookboughtthe Oculus VR companyfor $2 billion in 2014 [31], Luckeyreleasedanew versionofOculus Rift called DeveloperKit 2(or DK2). Thisnew versionﬁxed and improved upon some of theoriginalheadset’s ﬂaws suchasswitching the technology powering theirdisplayfrom LCD to OLED, decreasingthe latency of the headset from 60 millisecondsto30milliseconds, and inserting entirely blackframes in between other frames to see smoothly moving images [87]. The improvements also helpedwith reducingthe occurrencesofmotionblur whichisone of themain reasonsfor motion sickness [102]. The acquisition of OculusVRbyFacebookdid notchange the maingoal of making games but expanded the use of it in other areas suchaseducation andhealthcare with social networking built-in.

Facebookbuyingthe Oculus VR companywas adeﬁning moment in VR’s history because VR gained momentum after this. Sonyannouncedthe developmentofaVR headset for thePlayStation 4(PS4) under the name ProjectMorpheus[39]which then evolved and became apart of theequipment for PlayStation5 (PS5)VRgames. Google joinedthe race with the release of theGoogle Cardboard [55]. Google Cardboard(Figure2.3)is alow-cost and do-it-yourself(DIY)stereoscopic viewer forsmartphones.Itworks by placingasmartphoneatthe optimal distance away fromthe lenses thatcreate a3Deﬀect whenhelduptothe eyes.However, it requires compatible appstowork with.Samsung Gear VR [139]announcement in 2014was anotheradvancementfor VR. Samsung Gear VR, aheadset,uses Samsung Galaxy smartphones as aviewer with similarbuilt-in functionalities as Google Cardboard has. It then became apart of Sony’sPlayStation VR (PSVR) in 2016.

In 2015, theuse of VR expanded and became widelyavailable to the general public: • The Wall Street Journallaunched aVRrollercoaster that followedthe ups and downs of theNasdaq StockMarket.[137]

• The BBC created a360-degree video where usersview aSyrianmigrant camp. [106]

• The Washington Post released aVRexperience of theOvalOﬃce at theWhite

8 2.1. Virtual Reality

Figure 2.2: An interviewer tries out one of theﬁrstprototypes of Oculus Figure 2.3: AvarietyofGoogle VR at E3. [42] Cardboards. [54]

House Correspondents’ Association Dinner. [1]

• RYOT, amedia company, exhibited Confinement, ashort VR filmabout solitary confinementinUSprisons. [138] More releasesfollowedin2016 that focused on thefree movementofuserswhile wearing aheadset.HTC VIVE SteamVR headset [134]was one of them. This wasthe first commercial releaseofaheadsetwith sensor-based tracking whichalloweduserstomove freelyinaspace.Two years after that Facebookreleasedits untethered OculusGo headset [117].

Further developmentssuchasmanycompanies developing theirown VR headsets including Google,Apple,Amazon, Microsoft, Sony, and Valveaccelerated theadvancementfor VR headsets. ValveIndex[71]was released in 2019 and is currentlyifnot thebest one of thebestVRheadsetsonthe market [47]. Itprovidesanoptimized pixellayoutwith dual1440x1600 RGBLCDs greatlyreducing the“screendoor” eﬀect [113]VRheadsets hadtodeal with especiallyinthe early stages of developments.Moreover, the headset runs at 120Hz withanexperimental optionof144Hz improving the realismand optical comfort of theuserswhichalso reducesthe possibleoccurrenceofmotion sickness[78]. Besides thesefeatures,increment in ﬁeldofview (FOV)to130 degrees (perceived as 120) makes the users feelmore presentinthe experience [75].

Virtual realityhas signiﬁcantlyadvancedand is nowbeing used in avarietyofways, fromprovidingimmersivegaming experiences, to helping treatpsychological disorders, to teaching new skillsand more.Now thatweare aware of importanttechnological advancements in VR, thenextsubsectiondives into acollection of application areas of VR and informshow diﬀerentareastakeadvantage of these improvements.

2.1.2 ApplicationAreas VR has attractedalot of peopleinthe last decade which led companies to adoptand improve it [122]. With the helpofthe tools VR brings to thetableusersare ableto

9 2. State-of-the-Art

manipulatethe simulated world in anatural way. Sincethe simulated world canbe designed in an infinite number of possibleways, VR opensmanydoors forpeople to get creativeand achievetheirgoalsindifferent areas. Figure 2.4 showswhichapplication areas VR favors in termsofmarket share. The remaining of this section focusesonhow VR got embracedbydifferent application areas and what kind of great benefits VR providedthem.

Figure 2.4: Global VR headset marketshare, by application, 2020 (%) [130]

1. Gaming: Gaming with VR gives playersatruly immersive,first and third-person perspectiveofgame action. VR letsplayers experience and influencesthe game environmentthroughavarietyofVRgaming devices and accessories, including VR headsets, sensor-equippedgloves, controllers, trackers, and more. The next subsection goes into details about theseinteraction devices and methods. VR games can be playedonstandalonesystems, specializedgame consoles, or using PCsand laptops thatcan powerVRheadsets. PC and console-tethered headsets usually have better performanceand provide amoreimmersive experience,while mobileheadsetsare relatively inexpensiveand easier to set up and use.Although the bodily movements in real lifeare nottranslated to thatinVRfor standalone headsets exceptthe headrotationstoview the space in 360-degreeenvironments, companies suchasFacebook,Google,and HTC are developing cheaper mobile VR devicestoattract more users to adoptVRheadsets[95]. Gamers have ahigher average outlayfor upgradingtheir gaming PCs and consoles compared to people who do not indulge in gaming. Thishas encouraged companies to capitalize on VR games within the reasonable pricerange for gamers[136]. These VR games have the same scopeastraditional video games includingsingle, cooperative, and onlinemultiplayergames. Some of thesegamesplace players in physical combat environments,while others provide more relaxing letting players traverse worlds andvariousspaces. Other VR games takeplayers on adventures by challenging them to solve problems and explore unknown places. Section 2.1.5 gives more insight into different typesofgames and provide examples.

2. Entertainment: Although gaming is alsoapart of theentertainment application area, it deservesits ownsection because of theinﬂuenceitalonehas on the

10 2.1. Virtual Reality

market. Besides gaming, VR has other applicationsfor entertainment suchas providingvirtualmuseums [136]and galleries [8]. These setups make visitors the centerpoint of interactiveexhibitions so thattheycan takeatour in thesevirtual environments.Some of theseenvironments alsoprovide scene manipulation options suchasarranging theposition of artworks and changing thelightingand color of the walls as needed.Virtualthemeparks[32]are another great exampleofusing VR for entertainmentpurposes.VRgives peoplethe opportunity to visit theme parks and joinrides suchasTronatShanghaiDisneyland [131]and Jurassic World The RideatUniversalStudiosHollywood [63]while they are sitting on theircouches. Anotherentertainment source VR provides is letting peoplejoinmusicconcerts and be on thestagetoexperience livemusic. Virtual concerts[86]come with many beneﬁts forthe userfrom seeing admiredartists withouthaving to leavehome, to notworryingabout getting agoodseat,tobeing abletoadjustthe volume, and more. Although theseremoteentertainment opportunities come with beneﬁts there is still room to improve. Improving the visual qualityand making the audio more spatial would be essential improvements to increaseimmersion and thereforethe user experience.

3. Healthcare: Due to VR’s interactive natureand simulativeaspect,medical train- ingand mental healthrehabilitations stood forward for this application area. Medical and dental students have begun using VR to practicesurgeriesand procedures[160], allowing foralearning environmentwithout having consequencesof making mistakes. Therefore, therisk of inﬂictingharm on patientswhile practicing is eliminated.OssoVR [181]isone of thewell-known platformsthat provide surgical training and assessment. With the helpofVR, studentscan develop skills in various simulations which can later be applied in real-worldscenarios.Besidesthe beneﬁtof traininghigh-skill personnel, VR creates agreat opportunity to optimize costs[27]. Patienttreatment has alsobecome one of thecore application areas in healthcare. Pain managementisanexample where VR capturesthe mind’s attention and blocks painsignalsfrom reaching the brain [14]. Stress and depression treatments are further examples in this area. Moreover, VR alsoprovedtobeapromising and motivating platformtosafely practiceand rehearsesocialskills forchildrenwith Autism SpectrumDisorders (ASD) [29].

4. Education: VR provides various ways to enable education between studentsand teachers. VR education gives theopportunity to makelearningexperiencessocial by allowing students to communicatewith each other. Using avatarsand mapped facialexpressions [38], studentscan come together to discuss, synthesize, and learn from oneanother. All of thesecan be achieved by distance learning [128]. Students canbeput together in thesame room with digitalrepresentationsof themselves while teachersguide them through theirknowledgeand experiences. Anotherpossibility VR provides is letting studentsexperience placesacross the world without leaving the classroom. The technicalpart of this possibilityincludes using the 360 VR technology.360 VR contents are interactiveand immersive

11 2. State-of-the-Art

experiencesthat completelysurrounds auser as if they are standing in themiddle of ascene. The user can look in anydirection, allowing them to seeand interact with thecontent as they would in reallife [2]. Real-worldlocations are captured with special equipment using 360 VR and then thefootage is used to createthese captured locations into VR environments.Although VR is currentlynot as popular as other application areas suchasgaming and healthcare, thegrowth of VR within education in previousyears [72]shows potential forVRtobecome one of themost usedlearning tools in near future. ClassVR [180]isastep in the right direction to expand thehorizons of VR in education. It presents an open platform,supporting virtual,augmented, andmixedrealitycurriculum content, as well as allowing studentsand teacherstocreate, upload, and sharetheir owncontent,creatinga collaborativecommunity of global educational resources.

5. Retail: VR usage favors both retailersand customers in this application area. The focuspoint of using VR from theretailer’sperspectiveistrainingemployees. In 2017, Walmart provided VR headsetstoWalmart TrainingAcademies to train associatesinhandling daily tasks and situations such as managing thefrozen section and various events likeBlackFriday[69]. Anothermention-worthyVR advancementinretailiseBay’sVRstore whichfunctions via gaze-based interaction. eBaylaunched theworld’sﬁrst virtualrealitydepartmentstore in partnership with Australian retailerMyerin2006 [104]. Inthis virtualshop, customerscan select theirareas of interest at thebeginning of theexperience and thestore builds itself aroundthese needs.Customersare additionallyable to browsethroughthe products, gain detailed information aboutthem and purchase them.

The application areas of VR are,ofcourse, not limited to theones listed above and the onesseeninFigure 2.4, however, this sectioncovers onlysome of themost important ones. VR needsvariousinteraction techniques and devices to serve its purpose in order to enable human and computerinteraction in these application areas. The next section dives into these diﬀerenttypes of interaction techniques and devices.

2.1.3 InteractionTechniques VR userscan enhance theirexperience in virtualenvironments by increasingthe level of immersionthey perceive. One of themost importantwaysofachievingthis is using various interactiontechniques thatwould makethe environmentfeel natural.This section exploressome fundamental interactionconceptssuchasselection,manipulation, locomotion, and social interaction with thespecializeddevices that enable theseconcepts.

1. Selection: Selection involves telling thesystem whichobject or UI element the userwishes to interact with.Once an object or UI elementisselected it becomes the center of focus, so further interaction inputscan be processed forit. Selection can be performed using controller input, gestures,orgaze. Vanacken et al. [173] came up with design guidelines for selection techniquesthat include the selections in

12 2.1. Virtual Reality

virtualenvironments to be fast, accurate, easy to understand, produce lowlevelsof fatigue,and more. The devicesthat were developed in thelast decade followedthis suittoimprove the qualityofuser experience.Controller input is one of themost widely used techniquesfor this purpose. In this technique, avirtual laser-pointer (ray-cast)isﬁred fromthe controller to select objects. The user can change the controller orientation to aim thelaserbeam at desired objects. Although as of right nowthere are diﬀerentvariationsofVRcontrollersonthe market (Figure 2.5) that areused in manyapplicationareas, this type of selectiontechnique is stillused. Using gestures is anotherway to selectobjects in virtualenvironments.

Figure 2.5: From left to right: HTC VIVE [178], SonyPlayStation Move [126], Oculus Touch[118], ValveIndex[70] controllers.

Precisetracking of hands and fingersisarequirementinordertoachieveselection via gestures. Leap Motion controller [166]was one of thefirst devicesthat achieved finger tracking in short distances. It is basedonanopticalhand tracking module thatcaptures themovements of hands withoutany further requirements suchas wearing apiece of clothing. Manus Prime II [101]motion capture gloves areanother exampleofprecise finger tracking thatinvolves wearing asensor-equippedpiece of clothing. As thetechnology for handtracking evolved,this type of tracking started to get integrated into VR headsets. Newer devices suchasOculusQuest [119]support nativehand tracking. Common interaction techniquessuchasusing alaser beam cast from ahand coupled with apinchgesture can be usedtoconfirm the selectionofanobject. Nearby objects can, of course,begrabbednaturally by the visual representationsoftrackedhandswithout anyfurther combinationof selection techniques. Gaze-basedselection involves the head-pose or actual eye-gaze which can be tracked by the gyroscopes inside VR headsets[92]. Theselection interface usually consists of areticleoracursordisplayedinthe virtualworldasseeninFigure 2.6. The process of selecting through gazingstarts with the userlooking directly at the object.Then the selection canbeconfirmedvia either an external controller input or staringatthe targetfor acertain amountoftime. 2. Manipulation: Once an object is selected,the usermay alsowanttomanipulate the object.Resizing, moving, reorienting, scaling, and rotatingitare some of the available manipulativeactions theuser can apply to objects. The limits of these

13 2. State-of-the-Art

Figure 2.6: An examplefor agaze-based selection cursor in Unity.[94]

interactions depend on theavailable inputcontroller’scapability. These canchange from simply rotating the controller itself to complicated actions such as performing hand gestures.One of thewidely usedmanipulation techniquesissimply rotating an object just to inspect it while holding it in possession. If theheldobjecthas acomplex structure and justrotatingthe object is not suﬃcienttoinspectitin detail, then it might requiresimultaneous inputs from diﬀerentdevices suchas multiple controllersortracked objects suchasavatar hands[91]. Inthis case, while theobjectcan be heldand rotated with one controller,apart of theobject can be furthermanipulated by the inputs of thesecondcontroller.Moreover, the usercouldevenhold areal object in hand that is trackedbyexternalcameras and manipulateitwhichwouldyield haptic feedbacktothe user. Anotherway of tracking objectsisusing special trackers suchasVIVE Trackers [179]thatcan be attachedtorealobjects. The user then can manipulatethese objects e.g.with their trackedhands or feetinthe virtual world.

3. Locomotion: While selection and manipulation focusonthe interactionwith objectsinthe virtualenvironment, locomotionenables usermovementwithin the virtualworld.Thesemovementtypes mainly consist of repositioning and reorienting the user.Thereisadecent numberoflocomotion interaction techniquesthatare usedwidely in differentapplication areas [94]. One of them is called “On-Rails” where theuser has no control overtheir movementinVR[6]. VR rollercoaster describes this experience best because theuser rides along while onlybeing ableto look around.The most important challenge on-railslocomotion interaction poses is reducingoreliminating the feeling of disorientation [94]. Section2.2.7 goes into details regarding this type of VR sickness. Gaze-directed steering[84]isanextensiontoon-rails movementtypewherethe user movesinthe directionthey look. The velocityofthe movementcan be constantor vary throughout the movementsegmentbydifferentinputtriggers. The Jumpcube [34]projectincludesvarious gaming applications where themovementisbased on gaze-directed steering. “Mission TU Mars”, asolar system flightapplication developedinUnity, includesthis type of locomotioninteraction techniquewhere the usertraverses the space and changesdirectionsbasedonthe directionthey

14 2.1. Virtual Reality

look. Teleport is another locomotion technique to traverse largespaces in ashort time. Userscan use controller-basedorgaze-based raycast to selectanarea of thevirtual environmentthey want to move to and trigger theteleportation by acontroller input. More advancedteleportation methods can includerotation speciﬁcations wherethe user canspecify the direction they want to face when theyteleport. Real movementalso counts as one of thelocomotion interaction techniqueswherethe usercan simply walk aroundthe virtualworld.However, walking aroundwithout seeingthe realenvironmentincreasesthe risk of collision with real-worldobjects. Somemanufacturers suchasOculusprovide some sort of proximityalert system to protectusers from possibleaccidents[116]. Other solutions to limitedtraversing areaproblems include omnidirectionaltreadmill simulators suchasVirtuix Omni Platform [68]and TheVirtualizer[76]thatuse aspecial platformtosimulate endless locomotion in everydirection.However, thesedevices are currentlyonly availablefor commercial providers and not for end-users. 4. Social Interaction: Social VR givesusers the opportunitytomeetother people and talktothem in virtualreality. The spatial presenceaspect of social VR can give peopleasense of belongingand fulﬁllmentinasimulated world. Thecurrentstate of the worlddue to theCovid-19 pandemic increased theseneeds immensely [149][88]. Socialinteraction includes some or all other interaction techniquespresented in this section, however, it usesthese interactiontechniquestoenhance the abilityof people to interactwitheachotherasthey are presentinasimulated world.

Thissection provided us with valuable informationonhow to use diﬀerentinteraction techniques in VR. Before using this informationand investigatinghow VR gamestook advantage of theseinteraction techniques,wewilllookintogame developmentinthe next subsectiontobuildabase forthe last sectionofSection 2.1.

Figure 2.7: The potentialofVRapplications by category.[60]

2.1.4 VR GameDevelopment The advancementinVRmade VR game developmentbecome apopular investment [73]. VR headset sales hittheir peak overthe last few years and thedemandfor especiallystandalone VR devices is expected to growdramatically at least until2022 [122]. According to research by the InternationalDataCorporation (IDC), VR and

15 2. State-of-the-Art

AR marketwill reach 15.5billioneurosby2022,and as seeninFigure 2.7 thevideo game sector will keep leading thehighest market value of VR applications[60]. Besides showcasing thepopularity and importanceofVRgame developmentinthe market, this bringsustoexplaining the crucial points of developing thesehigh-value VR applications. Instead of explainingevery gamedevelopment stage,wewillfocus on thepointsthat are decisive to the virtualrealityaspect of game development.

Gamedevelopment starts with agame idea and planning. During theplanning stage, the target audience should be deﬁned and thecharacteristics of thegame should be constructed. These characteristics should help with answering thequestion“Whyshould my game use VR?” [174]. Once theseinitialsteps are completed, thetarget VR devices for the game should be chosen.The reasons behind this decisionare tightly related to the genre and theplaystyle of thegame. Lightmobile VR is agoodchoice if the game does notrequire motion sensorsand headmovements.Thesetypes of gamesfallunder the category of mobile games. Google Cardboard is an example of this kind of device which also carriesthe title of being the least expensiveVRheadsetonthe market by costingaround €10 [54]. Premium MobileVRdevices suchasSamsung GearVR[139] and Google Daydream [50]are furtherchoices formobile games with an additional set of sensorsfor head movements.PCand consoleVRarethe high-endplatform options forgames. As explained in Section 2.1.2and 2.1.3, thesehigh-end VR headsetsprovide high-level immersion andvarious interactiontechniquesaVR game would need. The tools this equipmentoﬀertodevelopers possess ahigh range of possibilities to bring their game ideas alive and as imagined.

The next step would be decidingonthe type of graphics for theVRgame. AVRgame developmentcostdepends signiﬁcantlyonthe game’sgraphic design.Below is alist of typesone canuse for game graphics [23]:

•2Dgraphics •3Dgraphics •Photorealistic graphics •360 panoramicviews

As 2D graphics usuallyadoptthe cartoonish style, they can stilllookprofessional, detailed, and complex whichbringsthis option on par with 3D graphics.Onthe one hand,photorealistic graphics requiresigniﬁcant investmentand budget especiallyifthe game imitates nature but on theotherhand,they canprovide the most realistic aesthetics possiblefor agame. Theother option,360 panoramicviews, gives theopportunityto add apanoramicview to the background of thegames. Adding interactiveelements to the videocan, however, presents challengesand become computationally expensive[23].

The developmentplatform wouldbeanother importantdecision to makeduring the game developmentcycle.Although thereisadeﬁnite diversityofVRdevelopment tools on the

16 2.1. Virtual Reality marketfor the end-users, Unity [161]and Unreal Engine [44]takethe leadbecause of being free of charge and theirwide supportintools,graphics type,operating systems,and ease of use. Once all thesedecisions are made and other fundamentalgame development stages [124]are processed accordingly, the next stepwould be publishing.For this matter, there is avarietyofmarketsfor VR games that includeOculus Store [115], Google PlayStore [125], Apple App Store [7], Steam[172], and VIVEport [177]. Although the popularityofthesemarketsmay vary,they form the defaultway to distribute contenton arange of devices.

CreatingaVR game is at basenot much differentthan developingatraditionalvideo game. Thelimitations,advantages, and additional requirements it bringscreate that difference during the developmentprocess. This sectionclarified howdeveloping aVR game has itsdecidingpointsthatwouldaffect the outcome significantly. Nowwewill look into some of themost successful games in VR history from differentgenres thatare playedbymillions.

2.1.5Game Releases This section is an overviewofsome of themost successful VR games on themarket.The maingoal of this subsection is to investigate diﬀerenttypes of games whilelooking into thereasons behindtheir success.

Figure 2.8: Traversing optionsinHalf-Life: Alyx. [11]

1. Half-Life: Alyx: Half-Life: Alyx[151], releasedin2020, is aﬁrst-personshooter (FPS) game that tellsthe story of an impossibleﬁghtagainst avicious alien race known as theCombine [151]. The maingameplay consistsoflooting and shooting enemies that are encountered throughoutthe game. Half-Life: Alyxisconsidered one of themost successful VR games in VR history [89]asitbecame Steam’s [172] best and most rated VR game less than ayear after launch. Valve’s game designers RobinWalkerand GregCoomer stated thepointsthatmade thegame asuccess

17 2. State-of-the-Art

story in an interview with Norman Chan [140]. Besides its beautiful graphics, the game providessimultaneous 2-handinputtomakethe playermore immersed with theuse of specially designed avatar hands.Players areable tointeract with many objects in the areawithdiﬀerentinput combinations applied to controllers. Moreover, the duo informedthatthe densityofinteraction played acrucial role in constructing theenvironment. Because of thehigh number of interactable objects in the environmenttesters tend to traverse the space slowerthanaplayerwould do in anormal video game. Thischangedthe way they designed the levels in the game and made the interaction with objectsrewarding. Anotherimportant pointmentionedwas theway players traverse in the game. Theydid not want to ignore the ability to traverse space and made it for playerssothatthey canmove slowlywiththe help of controller inputs. However, they still kept the possibility of blinking fromone pointtoanother to appeal to diﬀerenttypes of gameplay. Figure 2.8 displaysthe typesofmovementinthe game.

2. Beat Saber: Beat Saber [43], releasedin2019, is aVRrhythm game that evolves aroundslicing blocksrepresenting musical beats with apair of contrasting-colored sabers. In an interview [16]one of thegame designers,VladimirHrincar, mentioned that thesurrealisticneon environmentcreated forplayers is inspired by the movie TRON: Legacy [105]. Beat Saber provides theplayertwo lightsaberswhichcan be controlled by rotating the controllers. As thecubes of differentcolors that are supposed to be slicedflytowards the player, the playertries to slicethe cubewith the lightsaber of matching color (Figure 2.9).All levels created in thegame have differentdifficultylevelswhichencourage players to retry and beat theirscores. Although thegameplay is prettysimple the game became popularonthe market and madethe game one of themost successful VR games.

3. TheRoomVR: Dark Matter: The Room VR: DarkMatter[46]isthe first VR game of thewell-known puzzle video game series The Room [45]. Itexpands various typesofpuzzles aroundsmallenvironments at first before luringplayers into bigger places such as an ornatechurchthat holds itsown seriesofsecrets. Each scenehas acollectionofhot spots for players to stand in,lookaround, grab objectstoadd to theirinventory,and try to figureout what is goingon. Theclues players findthroughout thegame teachhow to think about these puzzles for future reference as much as howtosolvethe particularpuzzle in front of them [82]. The occurringeventsand the dark atmosphereinthe game add thehorror genretothe game. Interaction with in-gameobjects is performed by apair of avatar hands that are directedbycontroller inputs(Figure 2.10). Traversingthe space only consists of theteleport mechanism similar to in Half-Life: Alyx.

4. Microsoft FlightSimulator: Microsoft FlightSimulator[108]isaflightsim thatoffers itsplayerbase afirst-personviewpointtoflyoverthe whole world while in acockpit of aplane.Players canexamine allthe buttons and switches areal plane cockpit would offer up close. The simulationconcept providesahigh levelof

18 2.2. GameDesign

Figure 2.9: The player has to slice Figure 2.10: Players use theiravatar cubeswiththe correct ligtsaber of handstointeract with various ob- color. [62] jects. [80]

immersionasplayers takeoffand land at airports aroundthe world, fly through the cloudsand admire thelandscapes below. If players choose to just enjoythe flight, the game’sautopilotsystem takes care of thechallenging part of controlling aplane. However, the option to feel like areal pilot is stillthere by taking overcontrol of everything in the cockpit [100]. The interactionpart of the game consists of controller inputswithout anyin-game bodypart representations. MicrosoftFlight Simulator’ssandboxstyle of gameplay lets players enjoythe sight and provesthat VR games can exist without complicated mechanicsand still be successful as a game [164].

So far, the thesis explained the virtualrealityside of themaintopicwith memorable mentions about gaming and game design aspects. The next section goes moreintodetails about the game design topic andprovidesbroad information about itsbuildingblocks.

2.2Game Design

2.2.1Deﬁnition of Game Before givingdetailedinformationabout game design,itisimportanttounderstand what really “game” means. Thissubsectionfollows ratheraphilosophical approachwith quotes fromrenowned researcherswho were or are stillhaving arelationship to games thatwill helpwith comingupwith an acceptabledeﬁnition for “game”.

“A game is something youplay.”This is most likely the simplest form of game’sdefinition but it does notgiveusany details ratherthanstating thatitissomethingyou play. “A game is something that is fun to play.” is another definition everyone canagree on which also includesthe fun aspect.Understanding the building blocksofadefinition is as important as understanding theword youare trying to define, hence“fun” and “play” needtobedefinedaswell. Having“fun” is usuallyassociated with having experiencesthat givepleasure.However, “Fun is pleasure.”isalone not good enough because reading your newspaper in themorning while having acoffee cangivepleasure but it does not mean

19 2. State-of-the-Art

your morning routineisfun. Having fun with somethingrequires that something involve surprises [143]. “Fun ispleasure withsurprises.” is asoliddeﬁnition that distinguishes fun from pleasure. “Play” is rather hard to expressalthough we all know what play is when we see it.The German playwright, poet,and philosopher FriedrichSchiller deﬁned playasfollows:

Play is the aimlessexpenditureofexuberant energy. [48]

Thisdeﬁnition expressesthe outdated surplusenergytheory [107]ofplaywhichclaims thatthe purpose of play is to expendextra energy. It also states that play has no goals, which it most certainlydoes.

Early-twentieth-century philosopher Goarge Santayana describes playas“whatever is done spontaneously and for itsown sake”[112]. Thisdeﬁnitionmakes sense to an extent because play is often spontaneous whenwedescribethe playfulness of agame. However, thatisnot alwaysthe case when we think about competitivegames.The participantsof competitivegames have along preparation time. Regardlessofthe competitiveside of plays, spontaneity is an importantpart of play.“Forits ownsake” partofthe quote can be interpreted as peopledowhatthey liketodo. Thisisalsoanessential characteristic of play because if we do not like to do it, then it is notplay.

“Playismanipulation that indulges curiosity.” [ 141]byAmerican video game designer Jesse Schellisanother deﬁnition for play thatfocuses on thecuriosityaspect and the willful action of changing something youare curious about.

Although noneofthese deﬁnitions explain play perfectly,itshedslightonvariousaspects of what game can mean. Jesse Schell further deﬁnes game as follows:

Agame is aproblem-solving activity, approachedwithaplayful attitude. [142]

Thisisadeﬁnitionthatcovers many points of what agame can have and alsomakes us aware that problem-solving should be playful since notevery activitythatinvolves problem-solving is agame.

None of these definitions are perfectsince it is asubjectivetopic, howevernow we have ageneral idea of what game means. Thissubsectionalready sneak-peaked some of the game design elementsthat are hidden in thedefinitions. The next subsection includes thesegame design elementsand more as it shows thecategorization of them by different views.

20 2.2. GameDesign

2.2.2 DigitalGame Design Elements

Developing agame startswith an idea that usuallydescribes or hintsabout the game’s corewhichcan be described as aparticular pattern of actions that repeatsitself overand over[110]. Expansion of thegame’score happens by addingsome of thegame elements thatare availableinall games. Thisbrainstormingprocessshapesthe game with every added game elementthathelpstodesign thegame.

Before getting speciﬁc about game design elements, it is importanttomention basic elementsthat form agame. Forthis matter,there are diﬀerentviews with many common elements. Andreas Alexiouetal. expressintheir work [4]that game mechanics, narrative, and aesthetics formthe main digitalgame elements. Gamemechanicsare procedures and rules that are applied to thegame that describes howplayers canorcan not tryto achievetheirin-game goals.Theseprocedures facilitate the developmentofcognitive skills such as problem-solving,creativity, and spatial skills [57]. Section2.2.3 gives more insightintogame mechanics. Anarrativeorstory is aseries of events that unfoldinthe game. With the helpofthe story element,players canconstruct realityand make sense of theenvironmentthey experience [162]. On the one hand, branching and emergent stories are not alwaysthe case while designing games, however, even in games where storytelling is not essential suchasinPacman [183], it is stillpossibletoatleastguess the reasons whytheirworldsare the waythey are.Onthe other hand, avast majority of games rely on good storytelling to drivethe game and to immerse players further into the simulated worlds.Some adventure gamesprove the importanceofstory by the successthey achieved.“WhatRemains of EdithFinch” [36]isagreat exampleof an extremelysuccessfulstory-driven game in which theplayerisplaying as Edith, a memberofthe Finchfamily,thatdiscovers strange tales about her familymembers as she traverses through the huge abandoned Finchhouse. Gameaesthetics refer to the sensoryphenomena that theplayerencounters in the game [148]. Inother words, it is howgames look, sound,taste, smell, andfeel. Aestheticscount as acrucial aspect of game design sincethey have the most direct relationship to aplayer’s senses [143].

Figure 2.11: The Elemental Tetrad[143]

21 2. State-of-the-Art

Jesse Schelladds the “Technology” element to the mentioned core design elementsabove and describes thesefour coreelements as “Elemental Tetrad” as seeninFigure 2.11 [143]. He states that technology does not alwaysmean “high technology”but anytooland interactionthatcan makethe game work as it is supposedto. Whilechoosing the right technology enables your game to accomplishcertainthings, it alsoprohibits the designer fromdoing otherthings. Moreover, it is also essential for these fourcore elements to work in harmonyand beneﬁt fromeachother. When aset of gamemechanics is consideredto be implemented, the technology should be able to support it. Additionally, the aesthetics should emphasizethese gamemechanicsclearly to players and thestory should helpthe mechanicstomakesense to theplayers. Forthe sake of harmony, similar requirements alsoapply to other coregame design elementswhile characterizingthem.The game mechanicsshould strengthen the story,aesthetics should reinforce theidea of thestory, and thetechnology should suithow the particular story playsout.From the aesthetics pointofview,itisimportanttochoose therighttechnology to provideand amplifythe certainlookand feelthatisplanned to make players experience.Astorywith aset of events lets theaesthetics emerge at therightplaceand have the biggest impact [3].

Thecore design elementscan be furtherexpanded suchasGeorge Kalmpourtzis didwith his “Elemental Pentad” [3]. Here, however, thedesign purpose of thegame becomes educational.Kalmpourtzis believes thatthe needof“pedagogy”asthe ﬁfth element is highly required in the basicfundamental elements of educational games. Inhis design, everyotherelementshould complementpedagogy directly and improvethe experience forits users.

Besides fundamentalgame design elements, there are manyother digitalgame design elementsthat can be includedingames. The rest of this subsection covers some of these elementswhile explainingwhattheymean and howthey impact the game [143].

• Fun: Funisadesirable elementinnearly every game that increases thequalityof the game and theplayerexperience.Itisnecessarytoanalyze the game during playtesting to ﬁnd the segmentsthatdonot givethe feeling of fun.Theseparts should be revised by questioning the reasons behind the lackoffun.Improving the fun aspect of thegame is essential because keepingthe fun aspect at all stages of the game gives that game an enjoyable ﬂow.

• Surprise: Surprise is acrucial part of all entertainment and actsasabuilding block forgames. Sincehuman brainishardwired to enjoy surprises as researchstates [144], it is an essential element to increase the enjoymentplayers cantakefroma game. The previoussubsectionalready mentioned this element while deﬁning what agame is. That alone emphasizes the importanceofthis element for games but it is also necessarytounderstand howitcan be triggeredinvarious ways:

– The visual aesthetics in agame can be so incredible or one of akind that mightexceed player’s expectations whichcan cause apleasant surprise.

22 2.2. GameDesign

– The player can learn anew in-game skillthatcan enhance their abilities to move in the gameand explore areas that seemed impossible to reachatﬁrst. The capabilities this new skillgives to players cancreate afeelingofsurprise. – Horror games can containunpleasantsurprisessuchasjump-scares. – Used technology can surprise players suchasenabling interesting in-game interaction techniques players couldnot thinkof. – Game stories canend in unexpected wayswhichcan surprise players.

• Curiosity: Curiosity is an element that has adirect impact on theplayer’s motivation to play.The game should presentplayers with compellinggoalstoreach and givethem reasons to reach those goals.Asanexample,setting atimerto completeachallenge would plantthe question“Am Igoingtobeable to complete this task in the given time?” into player’s minds and makethem curious about the result. Anotherway to keep player’s attention and makethem curiouswould be to conditionthem to receiverewardsthroughout the game and makethem think about what thenextreward willbe.

• Problem-solving: Problem-solving involves encouragingplayers to solveproblems in order to succeedatthe game. Besides theobvious problems thatare thrown at players, there canbehidden or optional problems that need solving. Other than enticing playerstosolve problems throughcritical thinking, creatingadditional problems canattractmore players. Someplayers are onlyinterestedinsolving the crucialproblems andsomeother players, mostly completionists, do nothesitate to spendextra time to ﬁndthe hidden problems. This would alsoimprovethe time spentinagame and makeplayers keep comingback.

• Competition: Competition in games enables replayabilityofthe game by giving players somethingtoimprove on. Competition element can be added to agame in two ways: The players cancompetewith themselves and improve theirown scores or achievementsorthey cancompetewith each otherbybeatingeachother’sscores. Besides thereplayability, competitionalsoadds the socializing aspect to thegame if challengingone anotherispossible.

• Challenge: Challenges in agame makethe game moreappealing by givingplayers the feeling of struggletowards agoal. However, it is importanttomention that badly designed games have little challenge,ortoo much challenge.Ifthe game has alittle challenge it is highlypossible that theplayercan loseinterestinthe game very quickly.Too much challenge would alsomakethe game unplayable for most players and causefrustration instead of enjoyment. The games should have just the right amountofchallengetobesuccessful.

• Endogenousvalue: GregCostikyandeﬁnesgame as follows:

Agame is an interactive structure of endogenous meaning that requires playerstostruggle towards agoal. [58]

23 2. State-of-the-Art

The biological term “endogenous” shortlymeans“having an internal cause of origin”. In hisgame deﬁnition, Costikyan meansthat thingsthat have value in the context of thegame have value onlyinside of thegame. Thisgame design element as a measurementdescribeshow compellingagame is. Themore compellingagame is, the greater the “endogenousvalue”that is createdwithin the game. So, increasing the value of items or objectsthatare frequently usedbyplayers in the game also increases their attention to the gameand theirwill to playthe game.

Thissection provideduswith knowledgeabout digitalgame design elementsagame must or can include in itself. Oneofthe fundamental game design elements, game mechanics, however, needs more explaining,and therefore, the next section covers what is really meantwith game mechanics and gives detailsabout some of itscornerstones.

2.2.3 GameMechanics Game mechanics are theinteractionsand relationships between theplayerand the virtual environmentthatgives the game itssoul [37]. Thissoul includesmethods, rules, game dynamics,goals, and actions players are allowed to takewith thesolepurpose of satisfying the playerbyprovidingacompelling experience.The providedexperience is received in an endless cycleaslongasthe playerkeepsplaying the game. Thisendless cycle startswith the playerinteracting with avirtualenvironmentthatreceivesinputs from the playerand then changesits status basedonthe received inputs. Theplayer, then, analyzes thesechanges and makes decisions to takethe next stepinthe game. Thisseries of actions become repetitive once the playerinteractswith the simulated world again. Figure 2.12 visualizes this interaction cycle. The interaction cycleismoderated by the

Figure 2.12: Interactive cycle in the playexperience by Fabricatore [37]

rules of the game. Sincethe interactionaffectsbothsides, the playerand the game, there are differentrulesthe playerand the game itself should follow[17]. Therulesthe player should followcan be awritten setofrules whichcan be given to playersbeforestarting the game or they can be introduced to the playerasthey progress in the game, or they must be figured out by the playerontheirown. An examplefor sucharule canbethe requirements stated in the game to craft atool. In suchascenario, therules the game should followdependonthe progression theplayermakes throughoutthe game. If the

24 2.2. GameDesign playerhas thecorrect amountofmaterials to craft atool, the game should provide the playerwith thattool.

So farthis sectiongave the impression thatgame mechanicsbasicallyequalrules. On the one hand, this approachisadopted by some researcherssuchasLundgren and Björk[13]. Theydefine game mechanicsas“anypart of therules system of agame that covers one, and onlyone, possiblekind of interaction that takes place during thegame, be it general or specific (...)mechanicsare regarded as away to summarize game rules.” In this view, game mechanicsare accepted as low-level descriptions of game rules and thereisnoneed for adefinitional distinction between rules and game mechanics. On theother hand,there are counterarguments suchasstatedinProblem Machine Blog [98]: “A ruleisadirective of behaviorthatmust be observedfor thegame to proceed. Conversely, ‘mechanic’ is distant andimpersonal,implies something that happens as anatural consequence of something else occurring.”This view sees rulesasintimate, as they requirethe playerto activelyparticipateinorder forthe game to continuewhichalso requires the playerto have an understanding of rules.Incomparison, game mechanicsare impersonalwhich meansthat they do not require player participation or game understanding by the player.

Although rules are themost fundamental of all game mechanicsand they givethe game itsidentity, the rulesalonedonot deﬁne the game mechanicsofagame. Skillisone of theseelements where every game requires players to exercise certain skills. Based on the player’s skill level agame can feel challenging and givesomething to work towards for the player. Skill is alsoasource of enjoymentfor players as longasitstays interesting, rewarding, and balancedfor diﬀerentskill levels of players if the game possessesthese characteristics.Chanceisanother element of game mechanics. Leaving certainoutcomes to luckisagreat way to create surprises.Asmentioned in Section 2.2.1surprise is one of themost importantgame design elementsthatbring joyand excitement to players.

Since game mechanicsisapart of thegame design elements, all of itscornerstones can be furtheradded to the list of other gamedesign elementsmentionedinSection 2.2.2. The next section emphasizes theplaytesting step in game developmentand howitaﬀects the changesmade for plannedgame design elements.

2.2.4 Playtesting

Playtesting is one of themost importantdevelopment steps duringgame design. It can be described as aform of ausabilitytest where thetester can observe howplayers read and react to thegame. It is alwaysbetter to start playtesting as soon as possible.The time aprototype of the game is available the designer should start with playtesting.

Sinceevery comment from playtesters is crucialtoimproving the game, both positive and negative feedbackshould be embraced. Whilepositivefeedbacksignals thatthe designer has done something appealing, negative feedbackmakes thedesignerrethink the validityofthat speciﬁcpart in the game. Although positivefeedbackisgood to hearand

25 2. State-of-the-Art

importanttobuild up conﬁdence, negativefeedbackincludesessential information about improving the game further.The testershould nothesitatetoask playtesters what is wrongwith the game and explicitly encourage them to be as brutallyhonest as possible while givingfeedback[132].

Anotherkey pointischoosing theplaytesters carefully.Friends and family are good startingpointstotestthe game prototypewith, however, theirfeedbackwill most probably be biaseddue to the relationship. Sticking to onlyrelatives as playtesters can cause missingmajor ﬂaws in thegame,hence seeking peoplethatcan givehonest and constructive feedback is amajor steptoreceivethe informationneededtorevisethe game.

Welcoming negativefeedbackisone thing,but adaptingyour ideas according to feedback is another. Taking negative feedbacktothe heart canensure youdonot get tooattached to the speciﬁcsofanidea [132]. The same goal of an idea can be achieved in other ways which can also improvethe game at the same time.

Playtesting hasadirect relationship to the game design elementsthatare includedin the game. Thisenables playtesting to examine the game on multiple levels.Onone level, as an example, thegame needstohavethe right amount of challenge and be balanced. If the game feelstoo difficult to play for aplaytester which, however, cannot be the case foreveryone, the testercan ask questionsabout the parts thatmakethe game difficult forthatplaytester. Thereceived feedbackcan help rebalance thegame for thecasual audience.Onahigher level, aplaytestcan reveal howthe players react to agame’stheme, and whether thethemefits the mechanics [121]. If we continuewith the balance example, this higher level can be achieved if thechanges made in lowerlevelsmean something within the game. StardewValley’s[24]building crafting mechanicsisaconcreteexample forcreatingbalance with numbersand making these numbers meaningfulwithin the game. If theplayerwants to buildthe lowest tier barn, one set of resources theplayer needs to provide is 350 pieces of wood.Incomparison to this, ahigher-tierbarn requires 500 pieces of wood instead. Thishigher-tierbarn allowsthe playertohousemore animals in it.Itisfine to think about therequired number of resources just as anumerical value but it alsomakes sense becausebuilding abigger barn would logically need alot more piecesofwood.Moreover, playtesting canreveal if thegame is fun,and canassist with finding out thecorrect audience for thegame. Funisasubjective term, thereforedifferent groupsofplaytesters willhavefun in differentways. However, differentviewscan help the designer narrowdownthe audience and pitchthe gametothe players whowill likeit most.Given examplesinthis sectionshowthatvarious game design elementscan be tested throughplaytesting.

The next subsection is abrief reﬂection of previous subsections:game design elements, and game mechanics on VR which informs about limitations, advantages, and disadvantages of VR while applying the mentionedpoints to VR.

26 2.2. GameDesign

2.2.5 ReﬂectiononVirtual Reality ImmersiveVRexperiencesare basically illusions duringwhichusersmay experience being in anotherplacewhere theeventstakingplace are real [165]. In addition to place and plausibilityillusions, embodiment illusionisanother tool to makethe experience moreimmersive[103]. To achievethis,anavatar bodycan be used in the virtualworld thatcan represent player’s physical body. These illusions are themain powerofVRthat fools thebrain into believing thatthe artiﬁcial environmentand the events occurringin it are real.Aslong as theselies arebelievable players canlivetheseexperienceswithout breakingthe illusionand they canexperience them in person. Experiencingeventsor the environmentinpersonisthe mostdistinguishable feature VR games provide in comparison to games played on PCsand other similar screen-basedplatforms. However, the illusions are both the strength and theweakpoint of VR.While it is hard to create illusionsthatsatisfy players, they can be easily broken.The human brainisgoodat noticing unusualeventsand if thecreated illusiondoesnot makesense with theway the virtual world is presented,the illusioncan result in breaking the immersion.

Figure 2.13: Content-zone diagram for acomfortable user experience [5]

SinceVRisstill adeveloping technology,one must takethe capabilitiesofthe system and the peopleusingthe system into consideration. It is essential to understand the limitations the hardware bringsand howitcan aﬀect users.Once thesetechnical limitations are recognizedand necessary measuresare taken, the next stepisunderstanding users and the issuesthatmay comeupduring their VR experiences. There are various ways to solve these issuesorprevent them from happening. Oneofthem is providinguserswith physiological comfort.Ifthe gameincludestoo much movement,itshould be controlled by the playertopreventmotionsickness. Section 2.2.7 goes more into detailsabout the causes and solutions for it.Anotherkey pointisprovidingspatialcomfort to players. This

27 2. State-of-the-Art

perk is directly related to understanding the scalinginthe virtualenvironment. Players mayget uncomfortable due to small, large, or high spaces. Guiding players through the environmentisanotherimportantaspect to keep player’s focused and preventthem from having the feeling of getting lostinthe environment. Audio and lightsupport can be usedtoreveal paths in order to direct players into the directions they are supposedtogo. The same guidance methods that have provensuccessful areused whiledesigning other non-VR digital games. If the game includes UI elementsitisessential to takeergonomics into account.Algeret. al describes thecomfortable range of motion zones in theirwork [5] whichare illustrated in Figure2.13 and Figure 2.14.

Figure 2.14: Comfortableangles of neck rotation [5]

Soundisanother tool used in VR to increaseimmersion and createthe phenomenon of synesthesia [49]inordertomakeupfor thelackoftactilefeedbackinVR. Since tactilefeedbackmostly consistsofvibrationsthatare coming fromthe VR controllers, sound is agreattooltoenhance the feedback players receivewhen they touchobjects. Besides combining hapticfeedbackwith sound,providingholophonic sound is great to have because,inadditiontoleft andright channelsinstereophonic sound,holophonic sound allowsplayers to tell if soundiscoming from above, below, or behind [19].

Sincethe playeristhe center pointinVRand presentinthe virtualenvironment, artiﬁcial sensorysensations suchasvisual,auditory,and haptic feedback should be providedas much as possibletomakethe playerfeel morelikeapart of theenvironment. Although providingvisual and auditory feedbackingames is at an acceptable leveltomake thingsfeelreal to players, other sensations lackorare non-existent for VR experiences. Sensations suchasequilibrium [159]and olfaction remainunaﬀected partlybecause of theirunavailabilityingeneral or inaccessibilitytothe end-user.

28 2.2. GameDesign

Although non-VR games can createimmersiveexperiences, it is hard or not possiblefor them to reachthe immersion level of aVRgamecan provide to its users [129]. Because of theway VR aﬀectsits users, the usualgame design elementsand game mechanicshave to go through some alterations to be as eﬀectiveinVR. The ideas that create thegame design elementsmust adapt to the limitations and possibilities VR lays out to improve the userexperience.

Immersion is mentionedinthis subsectionand previoussubsections many times so far. It is essential to understand what it really meansand whyitisimportantfor VR. Thenext subsection informs about immersion and itstypes to give an in-depth understanding of it forgame design.

2.2.6Immersion Immersion is theuser’s engagementwith aVRsystemthatresults in being in aflow state [10]. Thisisasimple definitionofimmersion,however, it encompassessomuch thatits componentsneedtobeexplained further. StaffanBjörkand Jussi Holopainen proposed differenttypes of immersion in theirwork which can be listed as follows [13]:

•Spatialimmersion

•Emotional immersion

•Cognitive immersion

•Sensory-motoricimmersion

Björkand Holopainen described spatial immersion thisway [12]: Spatial immersion occurs whenthe simulated world is perpetually convincing. Theplayer feelsasifheorshe is really“there” and that the simulatedworld looksand/or feels “real”.(...) Spatialimmersionassuchisthe realresult of extensive maneuveringinthe game world in real-time games andcan even be occasionallyfelt in movies as well. The VR experience offers anew waytoexist in the virtualworld as aspatialpresence and keepsthe simulated world as Björkand Holopainenmentioned “perpetually convincing” with thehelpofencapsulation of head-mounted-display(HMD). The HMD servesasa remedy to immersion disconnects sinceuserscan stayconnected to thevirtualworld as long as theHMD is worn. However, wearing an HMD is not thesolesolution to these disconnects because technicalfactors and in-game implementationssuchasreconfigurable game worlds or invisiblewalls cancause further disconnects [97]. Locomotion is another major pointasthe playermay have to traverse the simulated world. As previously mentionedinSection2.1.3 there are many waystoachieve this in VR, however, the preferred wayneedstofeel natural and fitting to the world’s realitylogic.

Björkand Holopainen’stakeonemotional immersion is as follows [12]: 29 2. State-of-the-Art

Emotional immersion is obtainedbyresponding to the events that characters arepart of duringthe unfolding of anarrative structure and is like the immersionthat books,theater or movies provide.

Most VR games tend to have anarrativeside to the gameplay regardless of theirgenre because it helpsthe playerfeel moreinvolved and moreimmersedinthe game. As in anytypeofgame no matterwhatplatform the game is played on, the game’sstory can evokepositive and negativeemotions.Pallavicini et al. concluded in theirstudy [120] thatVRgamesappeartobeeﬀectivetools to elicit positiveemotionsand to decrease negativeemotionsand state anxietyinindividuals. Although this eﬀect of VR is possible, it is alsoproventhatVRcontent maylead to strong and persistentnegativeemotions [93]. The same study further found out that VR enhances thelevel of absorption into thescenarioand creates moreintensive emotionscompared to games played on non-VR platforms.

Cognitive immersion is theimmersion in abstract reasoningabout actions, events,and goals in games while playing the game [167].Freedomofchoice is the onlyrequirement cognitiveimmersion has which makes players consider what actions to perform throughout the gameplay. Cognitive immersion depends heavily on providing the right level of difficultywhichcan be achieved by providing consistentrealitylogic [168]. Consistent realitylogic can regulate having therightamountofdifficultybyremoving theneedto have to dealwith specialcases within acomplex environment. If thedifficultyisnot balancedcorrectly,low or high-level complexitymay cause players to experience analysis paralysis [169]ordowntime [170]whichwouldresultinplayers losing interest in the game.

Sensory-motoric immersion is theresult of feedbackloops between repetitous movements players make to perform the actions in the game and thesensoryoutput of thegame [97]. When aplayerperforms an action in agame, theavailable visual, auditory and haptic response that emerges has to be synchronized and makesense with what theplayerwould expect from that action. If the sensory response does not match theexpectations at all, it maycause adisconnect in immersion.Sensory-motoricimmersion is tightlycoupled with cognitiveimmersion in termsofcorrect use of complexity in the game. Keepingthe playerfeel challenged continuously would ensure and maintain sensory-motoricimmersion [97].

Keeping the immersion intactinVRgames at all times has thehighest prioritytokeep the players interestedinthe game, thus, providingthem with ahigh-qualityexperience.As mentionedinthis and previoussections it is not alwayseasy to keep thehigh immersion levelupfromadesign and technology viewpoint. The next section addsanother problem to the listofissues to solvewhile gaminginVR: motion sickness.

30 2.2. GameDesign

2.2.7 MotionSickness

VR motion sickness isprimarily caused by amismatchbetween movementcues sent to thebrain.Ifthe user is standing still in the real world butthe virtual environment aroundthe userismoving,this disturbs the brain’s equilibrium and theuser starts to feelnauseous. Nausea and dizziness countasthe most commonsymptoms of motion sickness in VR [163]. SinceVRmotion sickness is alsocategorized as simulator sickness, there areother symptoms suchasheadaches, feeling tired, eyefatigue, and disorientation [20]. There arealso additional factors that can influence theoccurrenceofVRmotion sickness in individuals. Astudy showsthatwomen are moresusceptiblethanmen to experience nausea in VR, which can be explained by women having awider field of view, hormonal differences,ordifferentin-depth cue recognition[18].

There are various factors thatinfluenceVRmotion sickness.Thesefactors can be divided into two categories as technology-influenced anddesign-influenced factors[163]. One of the technology-influenced factorsisthe headset that is used for tracking theposition of the player. First released 3-degrees of freedom tracking (3DoF)headsetsdid not provide free movementand were onlygoodfor viewing 360-degreevideos. In case theuser tries to move aroundwith a3DoF headset,the userwouldfeeldisorientationand unbalance because thescene would not move with the user. Compared to the 3DoF headsets, 6DoF headsets provide freedom of movementwithin the virtualenvironmentand solvemotion sickness problems 3DoF VR headsetswouldcreate. Using VR controllers is another factor thathelps with reducing motion sickness.Having handsinthe simulatedenvironment reducesthe effect of disorientation which can be caused by looking down in VR and not seeinganythingthe userwould normally expect.Latency is another technology-driven aspect that affectsmotion sickness. Oculus madeintensive researchonthe topic [40]to figureout the comfortable delay peoplecan accept between theactions they takeina real-world environmentand the representations of theiractions seenand heard in the simulated world withoutcausing motion sickness.Gaze behaviors alsoaffect motion sickness inVR. The unfamiliar eyemotion that is required to keep the virtualscene stable on the human retinacausethis unwanted effect [21].

Design-inﬂuencedfactors mainlyfocus on problems that come with rotation and locomotion in the virtual environment. As previously mentioned in Section 2.1.3teleportation is away forplayers to traverse the environment. It is proventhatteleportation helps reducing motion sickness [30]ingames.The way it works breaksthe illusion, however, it keepsplayers moving through the world withouttricking theirmind into thinking they are walking.Besidesteleportation,running in place [74]and redirected walking [90]are other ways to move in the virtualworld without creatingany conﬂict between thesensory and vestibular systems. As much as these methods eliminatethe occurrenceofmotion sickness,these methods are not preferred in games possiblybecause of theadditional space requirements and forcing players to physicallymovemost of thetime.Thereare other tricks learned by the developers thatusing static artwork or controlling where the playerfocusestheir attention decreases motion sickness[156].

31 2. State-of-the-Art

Motionsickness is still akey topic for VR and it is amajor problemtobesolvedinorder to increase the number of VR users. With the informationgiven about motion sickness in VR, thissubsection concludes the game design part of this chapter. Besides VR and game design, thedesignedgame for this work immensely focusesonclimbing.Therefore, climbing in general and especiallyinVRneedtobeclariﬁed whichispresented in the next chapter.

2.3 Climbing in Virtual Reality

2.3.1 Traditional Indoor Climbing Although this subsectionisdedicated to climbing in VR, one should have aknowledge base aboutclimbing in general since virtual climbing is based on traditional climbing at itscore.Thereare three mainpointsclimbers have to accustomthemselves to: the equipmentthey have to wear during theclimb, the ropesystem whichactsasasafety measure during the climb, and thetechnique they need to adopt to makethe climbing experience easier and safer [184].

Indoorclimbing presents the climberwith the opportunitytoclimbinacontrolled environmentwith extra safety measures. Non-wearable equipment can include mats on the ﬂoor to provideasoft landing in case of afall accident,carabiners on the walls to which climbers canattachthemselvesasthey progress furtherup, and chalk to remove moisturefrom handsand ease grippingthe handholds. Wearableequipment mainly consists of aharnessthat combinesawaistloopand twoleg loops tied together, and special climbingshoes thatgivemore edgingpowertothe climberasseen in Figure2.15. In addition to non-wearable equipment,the climberhas to have apartneralso called belayertohold them. The belayershould be very carefuland payattentionatall times to catchafall everytime the needarises. Climbing shoes are usuallyadvised to be worn without socksbecause during climbs with smallclimbing holds,the foot-to-shoecontact matters alot moredue to additional grasping power[184]. Forthe climbing systems that are basedonclimbing high, the climberneeds to be belayed. As mentionedbefore, this meansthat someone is belaying the climberonthe ground, and theropethat is attached to the climber’s harnessvia carabiners passes through an anchor ﬁxed on thewall and clipsintothe belayer’s harness as seeninFigure 2.16. Moreover, it is alsorecommended to make theclimberlet themself go in theearlystages of theclimbtoget afeeling for falling and buildtrust with the belayer. Anotheroption is to use an auto-belay[59], a device thatisanchoredtothe top of the wall and automatically takes up slackasthe climberclimbs. This methodisusually recommendedfor beginnersbecause it allows beginner climbers to focusononly climbing without worrying about whether thebelayer is doing theirjob properly.

Climbing technique is somethingthat needs to be learned by the climberwith experience. Professionalclimbers suggest climbers look at theirfeetinstead of theirhandsduring the climband plantheir movesbased on them. Climbing should be about walking

32 2.3. Climbing in Virtual Reality

Figure 2.16: Ropesystem Figure 2.15: Harness and climbing shoes forin- setup forindoorclimbing. door climbing. [150] [9] yourself up instead of pullingyourself up [184]. Adoptingthis move-setalsoreduces forearm fatigue alongwith holding armsstraightasmuchaspossiblewhile notusing them actively.Keepinghips overfeet as much as possibleand the torso close to the wall are further suggestions to stay strong and in control of your movements because your center of gravity stays in the middle of your body this way.

Mentionedpointssummarize thekey elementsduringaclimbinareal-worldscenario. The next subsection takes alookintohow climbing in VR is achieved by various applications so far and howmuchofthe informationgiven in this subsectionaﬀected the design of thesescenarios.

2.3.2VirtualClimbing

With the adventofVRinthe commercialscene,VRsports games alsobecame popular among consumers. Archery,ﬁshing, bowling, dancing, and climbing are some of themost notablesportsthat made into VR. Thissubsection, however, willfocus on theclimbing games whichisafocus pointfor the developed game Astroclimb.

33 2. State-of-the-Art

Figure 2.17: What competitionlooks Figure 2.18: The climber’s verticalmove- like in The Climb2.[25] mentonthe wall is mostly restricted.[81]

The Climb, developedbyCrytekfor Oculus Riftand TheClimb 2, developedfor Oculus Riftand Oculus Quest, are twomemorableVRclimbing games that made apositive impact on themarket.The games are characterized above all by appealing andrealistic aesthetics.Thereisawide varietyoflandscapes suchassnowy mountains, city with skyscrapers, and desertareasplayers canclimbin. Thegame focuses on enablingplayers to climbdynamicallyand quickly on certainroutes. Itispossible to compete against friends and have theirposition visibleasadditionalghostly glovesclimbing with you as seeninFigure 2.17. In order to control theavatar hands, players have to use the corresponding controllersOculus Riftand OculusQuest provide.The game’shaptic feedbackislimited by the signals thecontrollerscan issuetoplayers. Sincethere are no other bodyrepresentation models in thegame and thevirtualworld is not supported by anyphysical objectsinthe realworld, theclimbhappensonly with the player’s hand gestures and arm movements.Thesecharacteristics alsomakeitclearthatnomeasures like the ones mentionedinthe last subsectionare needed.

There are other similar games suchasToThe Top[154]whichcombinesclimbing with the platformer genre and Lucid Trips [153]that focusesonexploring surreal environments with abit of climbing in them. As in TheClimb series,these VR games provide players onlywith in-game handrepresentationstobeable to move around. Just like in The Climb, VR controllers are theequipment here to controlthe avatar hands in artiﬁcial environments.Kosmalla et al. investigated in theirresearch[25]the commonissue in these games, themissing feedback when interacting with virtual objects, to enable realistic, haptic feedback in arealistic-lookingvirtualworld. In theirapplication, they usedanartiﬁcial climbing wall as ahaptic feedbackdevice. The climbers have to use a head-mounted display with Leap Motion Controller [166]attached to be abletomove in the virtualenvironmentand have theirhandstracked at the same time.This setup allowsclimbers to actuallyclimbonthe physical climbing wall to be abletotraverse the virtual mountains. Since the physical wall has aheight of 2.5m,there were notany safetymeasures such as the useofropes or harnesses. As Figure2.18 shows,the climber

34 2.3. Climbing in Virtual Reality

(a) SteamVR Base Station 2.0 (b) HTCVIVE ProHeadset (c) VIVETracker

Figure 2.19: VR equipment usedfor Astroclimb. [176] is mostlyencouraged to move sideways.

Thissubsectionalready mentioned some of theequipment used whenitcomes to climbing in VR, however, there arestill other optionsinterms of equipment.Section 2.3.3focuses on thetechnologies usedfor Astroclimbwhile including some of these other options.

2.3.3 VirtualClimbingTechnologies Section2.1.3 already mentionedsomeofthe well-known technologies for VR, however, this subsectiongoesmore into technicaldetails and thepurpose of HTC VIVE Pro, VIVE Trackers,and the calibrationalgorithmsfor thedevelopedVRgame Astroclimber.

HTC VIVE Pro HTC VIVE Proisacommerciallyavailable head-mounted displayfor generating virtual realityvia connection to aPC. Here is alist of some of itsmost important features [145]:

• Resolution: 1440x1600 pixelsper eye(2880x1600 pixelscombined)

• Field of view-headset: 110 degrees

• Field of view-base stations: 150 degrees

• Refresh rate: 90 Hz

• Screen: DualAMOLED 3.5” diagonal

• Sensors: SteamVRTracking, G-sensor,gyroscope,proximity, IPD sensor

• Room-scale: Up to 10m x10m trackable area using fourSteamVRBase Station 2.0

35 2. State-of-the-Art

HTC VIVE Proheadset has some comfort upgrades which were missing in its predecessor HTC VIVE. The VIVE Proincludesasolidstrap, integratedheadphones,and acomfort system that consists of adialatthe back of the headset whichallows foreasy fit and comfortadjustment. Besidesthese improvements,VIVE Proalso hasenhanced ergonomicsthatbalancesout the weightofthe headsetfor game sessions. Astroclimb usesVIVE Prototrackthe position of theplayeronthe wall. Thetracking alsoincludes the use of 4differentbase stations. The basestations emit wide-angle two-dimensional IR laser beamsacross theplayarea.Eachtracked device contains an array of IR photodiodes connected to achip. This chip measuresthe time between theIRflash and being hit by the lasersweep for eachaxis. From this receivedinformation, the position of tracked objectscan be determined. Astroclimbuses fourstrategicallyplacedSteamVRBase Station2.0 fortracking.

VIVE Tracker The VIVE Trackerisasmallmotion tracking device that can attachtoany object in real life so that it can be trackedvia the base stations. It hasa270-degree field of view for sensing theSteamVRTracking basestations.The bottompart of the device deliberately avoids using sensors with the expectationthatitwill be mounted to something. Moreover, objectsshould be made of non-reflectivematerial to maintain maximumtracking performance,presumablytoavoid reflections fromthe tracking lasers which could confuse thedeviceoreventhe VIVE headset while in use [175]. Astroclimb usesatotal of eightVIVE Trackers, half of them mountedonthe wall to track the wall’s rotation, twoofthem placedonthe player’s handsand the other two fortracking the feet.

Calibration Astroclimb includestwo differentcalibrationprocedures thattakeplace at thestart of the application. Bothcalibration algorithms are implementedbyBSc. Ahmed Othman as partofthe Vreeclimber project[35]. The first calibration process calibrates the positioning of thehandsand the feetofthe player. Forthat to happen,the playerhas to wear two trackers on top of theirhands, and two of them on top of theirfeet. Onceall set, in astanding position, the playershould keep theirtoe tips and fingertips facingforward. In addition to that,their palmsshould be parallel to the ground. Figure2.20 shows how the player’s stance should be duringthe handsand feetcalibrationprocess.The second calibrationprocess involves aligning thephysical wall and itsclimbing holds with their virtualrepresentationsinthe virtualenvironment. In order to achievethis, there should be two visible trackers mounted on thewall on one side.Based on thedistance between the headset and thesetwo trackers on thewall,the position of theheadset is adjusted which results in aligning thewall. This concludesthe initialcalibration process for the wall. Sincethe physical wall keepsrotatingduring the game, theposition of theclimbing holds change with varying speeds.With the speed information gainedfrom the engine thatmakes thewall rotate and theposition information acquiredfromtrackingthe wall,

36 2.4. Related Work

Figure 2.20: The stance theplayerhas to takefor calibrating handsand feet. the climbing holds’positionsonthe wall update themselvesvia the algorithm which keepsthe climbingholds alignedwith their representations in thevirtual environment.

2.4RelatedWork

As mentionedinprevious sections, the decisions game developers make to designthe game and meet theusers’ expectations highly depend on thestate of thecurrenttechnology. Moreoever,game design in VR is stillaplayground for game designersand developers considering theimpactful growth of VR in game industry onlyhappened in theprevious decade as mentionedinSection 2.1.1and 2.1.2. Therefore, thefusionofgame design and VR will stilltaketime to be in harmony and appealing to users. Thissection introduces otherrelated research papersthatfocus on game design in VR.

Shelstadetal. investigateintheir research[146]how VR technologyimpacts thegame as user satisfaction by using the Game Use Experience SatisfactionScale(GUESS) [123] which is acomprehensiveand psychometrically validated game scalethatincludesnine subscales contributingtovideo game satisfaction. These subscales consist of various game design elementssome of which are already mentioned above. Theycan be described as follows: • Usability/Playability: Thissubscale describes theease of control inside of the game forthe player andwhetherthe game has clear goals for players to fulﬁll. • Narratives: Thisisthe story aspect of the game that can have an inﬂuence on player’s emotionstowards the story elementsofthe game which is also responsible for keeping players interestedinthe game. • PlayEngrossment: Thisperk describes the degree of interest agame can hold for the players. • Enjoyment: The fun factor describes thepleasure players canperceivebyplaying the game.

37 2. State-of-the-Art

• CreativeFreedom: Thisisthe extent to which the game is abletofoster the player’s creativityand curiosityand allowsthe playertofreely express his or her individualitywhile playingthe game.

• Audio Aesthetics: Thissubscale includes all auditory aspectsthe game oﬀers and howthey enrichthe gamingexperience.

• Visual Aesthetics: These includethe visualsinthe game and howappealing they appear to theplayer.

• Personal Gratiﬁcation: This perk involves the motivational aspectsofthe game suchaschallenge which can promote theplayer’ssenseofaccomplishmentand the desire to succeedand continue playing the game.

• Social Connectivity: Thissubscale describes thedegree to which the game providessocialinteractions between playerswith its tools.

Although GUESS representsabroad scalingtoolfor measuring player satisfaction,the researchstates thatthere should be doubts about itsevaluation simply because of theVR aspect of thegames. Considering VR provides aricher and moreimmersiveexperience, GUESS scores shouldvary foragame playedusing VR and no VR.

Furthermore, the study showsthat some of thegame design elementslisted under GUESS subscales are successfully applied to VR gaming experience and therewas asigniﬁcant diﬀerence in the overall satisfaction scores between the VR and traditional computer monitor experiences.

Nolan et al. emphasizeintheir study[114]playerexperience,comfort, and design processes thatare importantwhile designing games for VR. Theypoint outthe importanceof playercomfortand categorize it underphysical,psychological, andsocial comfort. While physical comfort focuses on theorientationand the movementofthe playerinthe virtual environment, psychological comfort states that the VR experience should refrain from trauma-inducingand unpleasant content.Ifthe game includes socialaspects, it should include safezonesand placesfor playerstorestand potentially remove theirheadsets to get out of that social environmenttorecharge. Section 2.2.5ofthe thesis prioritizes the physical comfort aspect of player’s comfort in general and providesin-depthknowledge about what Nolan et al.mentionedintheir research.

Besides player comfort,the studydirects attention to thepossibilities andlimitations of VR as well. These possibilities and limitationsinclude the interactiontechniquesin VR, playerexpectations, tracking,and locomotionmethods. Thesesubjects alsocreate an essential partofthe thesis thatismentionedinSection 2.1 and 2.2. VR playtesting is another topic of Nolan et al.’ sresearchwhichstatesthe importanceofitand what should be taken into account while performing playtesting.Section 2.2.4ofthe thesis is speciﬁcally related to this topic.

38 2.4. Related Work

Immersion and EngagementinaVRGame by Pradeepetal. [127]isanotherwork that involves VR and game design. The researchers compare thelevelsofuserengagementand task performance basedonaVRgame. The study furthermorefocuses on acomparison between desktopsand theHMDs andexplores exocentric versus endocentric approaches, the level of confusion factor,and the eﬀect of thevirtual avatarrepresentations. During theirobservations, they alsotakenote of thesituational awarenessofthe userwhen they playthe game. The goal of thestudy is to answer thefollowing questions: 1. What is thelevel of engagementthat the user experiences?

2. What is the task performance and time elapsed for thetask for eachuser within the designed time?

3. What pathdoesthe usertaketocomplete thetask? As seeninthe questions they usedsome speciﬁc game design elementssuchasengagement, problem solving,and playerperformance to get answers.

Alexander Lund’spaper [97]investigates immersion,game feel,and flowstates forVR, and howtheseelements caneitherenhance or reduce the qualityofplayerexperience. In order to support the investigation,the researcher makesuse of astory-driven VR experience called Norn [96]. The paper includes alarge varietyofdifferenttypes of definitions forimmersion which also inspired Section 2.2.6ofthe thesis.The author emphasizes that themechanics andinteractions designed for aVRgame should feel natural to perform and should not be taxing forthe players during extendedplaysessions. The designer should,moreover, keep theVRequipment andthe in-game interactions in mind while designing the game aroundthem.Asinpreviously mentionedpapers, Lund points out thesignificance of theplayer’s physical comfort while playing thegame. Besides thesepoints, world and player scalingform amajor partofhis work. According to Lund, the game should be designed forthe physical space provided. Thelocomotion in this designed areashould feel safe and should not cause disconnectsbetween the time before and after theteleportationsifthatisthe chosen locomotion techniquefor traversingthe virtualenvironment. Various sections of thethesis include knowledge about most of these keypoints mentioned in Lund’s work.

Desurvire et al.’s research paper [28]isanother example thatfocuses on VR and game design. They created in theirstudy design guidelines called theVRPLAYguidelinesto assist in evaluating and designing improvedVRuser experiences. VR PLAYguidelines consistofﬁve main categories called Usability,Playability, VR Immersion,Creative VR, and New PlayerExperience (NPE). These ﬁvemain categories have atotal of 33 guidelines which includessome of thementionedgame design elementsinthe thesis suchaschallenges, goals, engagement, andpresence. As Desurvireetal. state, notall guidelines areapplicable to allVRexperiences becausethe created VR experience may notcontaincertaincommon game mechanicstowhichtheseguidelines apply.This is another commonalitywith the presentthesis thatagame can not containall possible game design elements.

39 2. State-of-the-Art

Although thepresented related works in this subsectionvary by theirquestions to answer, the commonpoint is providingacompelling userexperience to the userwithin the designed VR game. The next mainsection goes moreintodetails about thedesignedVR game for thethesisstarting with the conceptionofthe game.

40 CHAPTER 3

ConceptionofAstroclimb

3.1 Requirements for Designing the Game

There were various requirements fordesigning Astroclimbwhichbranchout from the thesis questions. This sectionisthe starting pointtoexplain theserequirementsthat led to creatingthis speciﬁc concept of thegame.Abrief list of themain requirementswould be appropriate before explaining them in detail:

•The game should revolvearoundclimbingawall.

• The gameplayshouldbeasﬂexibleaspossibletoaddress adiverse gameplayer base.

•The game should be immersiveand compelling.

•Included game design elements should match theVRaspectofthe game.

Whiledesigning the game, themainfocus wasmaking thegame as ﬂexibleaspossible in termsofgameplay while keepinginmind thatthe game includes aphysical climbing wall. Taking advantage of theclimbing aspect of thesetup, theconception of thegame creates acleardistinctionbetween theexperience aplayercan have while playing aVR and anon-VR game. Astroclimbmakes theplayerinteract with objectsasmuchas possiblewhile givinghaptic feedbackwhichisone of themaindistinctions of this VR game compared to traditional video games. The ideaofinfact climbing aphysically presentwall alsoenabled physical training for theplayers. Enabling physical training in aplayful waywas another feature of the game that distinguishesthis game from other videogamesand even most VR games. Thesefeatures of thegame were to createa basistoinvestigatethe applicabilityofgame design practices to VR platforms. Applying common game design practices to aVRgame with thesefeatures would createafair

41 3. ConceptionofAstroclimb

testingenvironmentand helpwith answering whether these methodsare appropriate for VR experiencesornot.

In order to keep thegame immersiveand compellingtothe players at all times, the use of technology playedacrucial role in addition to theaesthetics that are used for creatingthe environment. Especially the calibration algorithms usedtokeep the physical objectsaligned with theirvirtualrepresentationscontribute to thelevel of immersion significantly. The technology and theaesthetics directly influence thegame feel.Game feelisacombination of differentaspects whichinclude tactile sensationthatdictates howentertaining or engagingthe act of playing the game is, howquickly the character responds to control input andhow much audio and visual feedbackitisprovidedfor doing something within the game [157]. Inaddition to audio and visual feedback, Astroclimb alsoprovides haptic sensations which enhancesthe game feel.

The gameplayinAstroclimbhas asubstantial inﬂuenceonthe chosen game design elements. Sincethe game mainlyrevolves aroundclimbing awall,most of thegame design elementssuchasproblem-solving,elements of surprise, physical training, fun,and competition have adirectrelation to what theplayeriscapable of doing in the scenery. As previously mentionedinSection 2.2.5VRcomeswith limitations and possibilities, hence the application of thegame design elementsrequiredadaptationsbasedonthe physical availabilityofthe players and other aspectswhichare discussed later in Section 3.3 in detail. The next subsection goes into detailabout the chosen design approachto createAstroclimb.

3.2 Design Approach

The game design idea is mostly affected by the structuraldesignofVreeclimber. As previously mentioned in Section 1.2 Vreeclimber’s structure is based on averticallyrolling wall thatcan enableclimbers to climbindefinitely.The physical structure neededa virtualrepresentation in theartificialenvironment, so the first steps were designing a wall with climbing holds on them that match the physical wall as perfectly as possible. The heightofthe wall and thematerial used foritwerethe most crucialpointsduring the design process of thevirtualwall. On the one hand, theheightofthe virtualwall has ameasurableinfluenceonthe usabilityand game feel.Avery highwall could reduce the usabilityfor some players thatare notused to climbing. This would additionally affect the game feel in away so that theplayers might just giveupinthe middle of the game becausetheir physical endurance for climbing couldnot match the strength required to finishthe game. The playtesting sessions alsoshowedthatthe initialheight of thedesignedvirtualwall wastoo much formost players so the number of gripblocks got reducedduring the development. On the otherhand,the heightwouldalso affect some of thegame design elementssuchasphysical activityand engagementinanegative way.Again as an example, ahigherwallmightcause theapplication of thephysical activityelementtobeunsuccessful by creatinganexhausting experience.Making the

42 3.2. Design Approach game physicallynot enjoyable would alsotakeaway the engagementaspect of thegame and render it unappealing.

The chosen material for thevirtualwall also plays akey roleindesigningthe game. Creatingafullytransparentmaterial for thevirtualwall makesupfor someofthe disadvantagesofclimbing aregular wall while enhancingthe visual aesthetics of thegame. If thevirtualwall were opaque, that would mostlylimit the view of theclimberwith side directions duringthe game besides seeingthe wall. As previously mentionedinSection 2.3.1climbers usuallyfocus on theirhandsand feetduring theclimbwhichmeans their focus of direction to thefront. Focusingonwhatisinthe front would alsomakethe objectsplacedbehindthe climbernot or hardlynoticeable. Giving atransparentwall to the playerand populating the backsideofthe virtualwall with interesting objects would improve the visual aesthetics of thegame.Since the player’s front view is mostlythe focus pointinsuchacase,this would alsoreducethe additional head movements the playerhas to perform in order to be abletosee theenvironment. These qualityoflife improvements in thegame would helpplayers with regulating theirstamina duringthe climbeﬃcientlyand reduce possible causes for motion sickness.

The root idea of designing Astroclimbinouter space comes from the discussionsduring Ms. NataschaMachner’s master’s thesis [99]defense. Climbing in outer space is something thatwould not be possibleatleastwith the technology we currentlypossess. The combination of this impossibility and the unknownknowledgethatlies in outer space encourage humankindtoﬁll this knowledge gap [147]. Thiscuriosityinducing hunger for informationmakes space an excellentthemefor games. The highnumberofouterspace related games on Steam [152]emphasizesthe popularityand successofusing outer space as agame environment.

The idea of having aclimbing wall in outer space automatically addsthe science-fiction genretothe game which also opensmanydoors forcreativity. In comparison to science- fiction, sticking to realitywouldlimit the designoptions especiallyfor agame that is playedinouter space. Although designing agame with an unrealistic setup gives freedom about ideas to thedesigner, it also addsthe challenge of making thegame immersive. It is importanttodesign theenvironmentinsuchaway so that thesetup can makesense to the playerand the playercan stillimmerse themselves in it.Inthis matter,Astroclimb providesthe needed immersion with differentaspects it possessessuchasaligning the physical and virtual objects at ahigh level,having futuristic-looking objects, matching soundtracksand effects, andastory thatmakes sense to players. All of these aspectsof Astroclimbwith thegiven gameplayoptions createagame feel that aimstosatisfy the player.

The design evolution of Astroclimbwentthrough some changestomatch the previously mentionedrequirements fordesigning Astroclimbbetter and improve the experience players canreceive from theadded game design elements.Besides changing theheightof the virtualwall, the way of keepingplayers safe and preventing them from reaching the

43 3. ConceptionofAstroclimb

very top of the physical wall wasaltered. Sincethe physical wall has acertainheightand the virtualwall is tallerthan the physical one, it is acommon occurrencethat the player reaches thetop endofthe physical wall during the climb. Whenthis happens,for safety reasons,players have to pause climbing until the wall rotates long enoughfor players to slide back to the planned climbable area of thewall.The ﬁrst idea wastoadd athickfog to thetop border of the climbablearea and make everything abovethat pointinvisible. After numerous playtestingplayers still tendedtoreachtothe climbing holds above the fogalthough they did not see them which showedthat fogwas not an adequatesolution. Furthermore, the fogprevented players from seeing someofthe gameplay cuessuchas an asteroidhitting the top of the wall causingthe wall to tilt. An alternativeway wasto givethe playeravirtualastronaut helmetand use its glass surface fordisplaying warning texts and information. The warning text is alsosupported with audio feedback. The playtesting afterward showedthatthe alternativesolution encouraged players to pause climbing whenthey sawthe warning text. Anotherimprovementtomotivate players to replaythe game wasachange madeinthe gameplay. Thenextsubsectiongoesmore into thegame design elementsAstroclimbpossesses and explainshow they are achieved in the game to give players an engaging gamingexperience.

3.3 Included Game Design Elements

Astroclimb’sconception includesvarious game design elements. Section 2.2.2lists onlya subset of thegame design elementsthatwere actuallyused in the presentgame. Those gameelementsand the additionally included ones are listed below: • Experience: The maingoal of Astroclimbistogiveplayers an experience they can not receiveanywhere else by climbing acelestial wall in outer space while they can enjoythe environmentand the events occurringthroughout the climb. The story of thegame, theaesthetics used to buildthe environment, the mechanics providedtoplayers, and theunique playstyle VR technology createshelptodeﬁne the essence of Astroclimb andbestowituponplayers.

• Surprise: Astroclimbinjects this game design element in various ways. Some of them just come with technology suchasthe precise tracking system forthe player’s handsand the high-resolutionperkofthe usedheadset which renders the environmentasifitwas real.Game aesthetics suchasgiantspaceshipswarping in and out all of asudden, the sound of an asteroidcrashing the wall, and thewhole climbing wall getting suckedintoablackholeare acouple of examples that create asense of surprise for players when they experience theseevents. The gameplay alsocontains some unexpected events suchastouching arelatively smaller climbing hold gives extrapoints.

• Curiosity: There are manywaysAstroclimbawakens the feeling of curiosity in players. Theway theyare injected into the game is mostly through visual aesthetics and game mechanics. At the start of thegame, theplayerﬁnds themselves in a

44 3.3. IncludedGame Design Elements

hangar waiting behind ahuge door to be opened. The possibilities behind this door should makeplayers curious about howthe game will play out. Anotherexample is when players are presented withdiﬀerent orbs that have the abilitytoenhance the glovesplayers are wearing in thevirtualenvironment. The intention behind the way they are presentedistomakeplayers intrigued about howtheirchoicewill impact thegameplay.Players being abletopickonly one of theorbs alsoaddsto the feeling of curiosity about howthe game wouldplayout if they were to pick another orb.

• Problem Solving: Thisgame design element is onlyachievablethrough gameplay in Astroclimb. In thegame,players gain points by interactingwith the climbing holds and as mentionedbeforethe points they gain from climbing holds is inverse to theirsize.Ifthe playerwants to get ahigherscorethey should seek the smaller climbing holds and traverse the wall basedontheir positions. Changing the route basedonthisgoal represents aproblem they can solvebyobserving the gripsand move on thewall accordingly. The enhancements gained from orbsadd another layertothisproblem sincethe enhancementschange the waythe player’s gloves interact with the climbing holds.Additionally, problem-solvingdirectly awakens critical thinking for playerstoovercome the problems thatare thrown at them.

• EndogenousValue: The most important itemsplayers care aboutinAstroclimb are theiravatar handsand the wall they climbbecause withoutthem they would notbeable to playthe game at all.Theseobjects arealsodirectly related to succeeding in thegame with ahigh score. Figuring out to which itemsplayers put value in, gives thedesigner thechance to makethe game morecompelling by increasingthe value of those items. Improving or changing themost valuable items to players in Astroclimbisachieved by addingenhancements to the glovesand changingthe climbinghold layout throughout the game.

• Goals: Although it mightseem like the sole goal of Astroclimbtoreachthe end of thewall, the main goal of thegame is givingplayers auniqueexperienceinVR. The game’sgoal is self-explanatory for players, however, the wayAstroclimbis designed gives players choices about howtoenjoythe game. Being presentinouter space alonecan be satisfying enough for some players and they cansee Astroclimb just as asandboxgame for having quality time. Players with acompetitivemindset can stilltry to go for scoringhigh scores and payattentiontotheir time score as well. Experiencedclimbers canfocus lessonthe aesthetics game provides andjust enjoythe physical activitypart of thegame.Enabling thesediﬀerent goals for players alsomakes thegame moreinviting to audienceswith diﬀerentbackgrounds.

• Fun: It is hardtodetermine alonewhether agame is fun or not. Only the feedback received duringthe playtesting canhelpwith assuring the fun aspect of thegame. As mentionedinSection 2.2.1the deﬁnitionofthe game includes problem-solving, playfulness, and goals.Includingthese elements in the game can at least be a starting pointtobeable to judgethe game as entertaining.

45 3. ConceptionofAstroclimb

• Uniﬁcation&Theme: Astroclimbhas aclearspace themethat is supported by manyvisualaesthetics suchasthe huge spaceshipthatbringsthe playertothe climbing spot, thenebulathe playerisable to gaze upon during theclimb, the black hole positioned belowthe climbing wall to encourage theplayertoclimbup, an asteroidbeltthat occurs at some stage of thegame, thespaceships thatwarp in and out,the moon colony, and themechanical interactable objects. All of these visuals in harmonygivethe game auniﬁedtheme.

• PhysicalActivity: The factthatAstroclimbincludesaphysical wall to climb gives playersthe opportunitytoperformphysical training as they play the game. Sinceclimbing is ratheratiresome activityfor playerswith no or little experience, it iscrucial to balance thegame so that players with no experience canenjoythe game as well. As previously mentionedinSection 3.2, corresponding measuresare taken throughout the designprocess to balancethe heightofthe virtual wall.

• Challenge: Astroclimbgives three diﬀerenttypes of challenges in the game. The ﬁrst oneisthe physical challenge everyplayerhas to facetomakeprogress in the game by climbing up thewall. Thesecond type is hidden in one of theoptions presented via orbsthatrenders some of the climbing holds invisible to the player. The thirdtypeinvolves beating your ownoryour friend’s scorewhichalso creates acompetitiveenvironment.

• Engagement: Playerengagementisthe level of continuationdesire experiencedin- game, during play,oroveralonger periodoftime when players dedicatethemselves to coming back and playing agame again and again [61]. Astroclimbtries to achievethis by the scoring system and givingthe playerasingle chancetopick an orb during theorb selection phase.The scoring system encourages players to play the game again to beat theirorothers’ scores. The orb picking system makes the playercurious about theoutcome of thegame if they were to pickanotherorb. Bothsystemsincrease the chanceofreplayabilityofAstroclimb. These game design elementsare all included in Astroclimbindiﬀerentareas. Although the application of thesegame design elementswas successful,there is alwaysroomto improve the game. The next subsection gives ideas about howtoimprovethe current state of Astroclimb with diﬀerent designapproaches.

3.4 Possibilities for Improvement

The currentstate of thegame wasgenerally satisfying for all theplayers thattested the game, however, it is still possibletoimprovethe game. The possibleimprovements includegameplayand the positioning of objects in the scenes.

The rotation mechanism of thephysical wall has aspeed limitwhichmakes pausing the climbacommon occurrenceduring the game. Although thesafetyside of this problem is takencare of as mentionedinSection3.2,the gameplaystill suﬀers because players

46 3.4. Possibilities forImprovement with climbing experience are toofast for thecounter-rotation speed of thephysical wall. Anew game mode couldbedesigned for players with climbing experience thatwould prevent them from pausing theclimbtoo often.This game mode couldfocus on making the playertraverse sidewaysonthe wall so it would givethe mechanism enough time to rolldown. Forcing the playertotraverse sidewaysmightrequire some limitationstothe freedom of theplayer. Providingthem with aroutetofollowwouldforce them to use a speciﬁc set of climbing holds, but in theend, it would be asolution for frequentstalling.

When the playerreachesthe end of theﬁrst part of thevirtualclimbing wall, amechanical owlappears at theleft backside of theplayer. Placingthe owlrelatively behind the playercaused some problems for players to notice the owland theinteraction of the playerseemed ratheruncomfortable whilepicking an orb.The positioning of the owl could be optimized whichmightimprove the usabilityand the overall comfort experience of theplayer.

The pointand time scoresare currently displayedonthe glovesofthe playeratall times, however, there is no waytokeeptrack of thepersonal bests or scores of other players. Agloballeaderboard could be agoodsolution for playerstocheckout the overallhigh scores whenthey decide to playthe game again.Creating agloballeaderboard would also improve the challenge aspectofthe game and act as an ampliﬁer for competition.

Of course,there is alwaysroomfor improvementand more ideas to makeAstroclimb moreappealing to players. This section covered some of thepossible improvements that can be applied to thegame. The next mainsection informs about howthe game was implementedindetail.

CHAPTER 4

Implementation of Astroclimb

4.1 Overview

Thischapter focuses on howAstroclimbisimplementedbasedonthe design concepts discussed in the previouschapter.First, the planning of differentscenesinthe game is explained by pivoting theobjects placed thatgivethe outer space and science-fiction atmosphere to thegame. The remaining aesthetics suchasaudio and furtherassets thatbuild and enhance thegame’satmosphere is handled as next.Gameplay is the followingmaintopicthatincludesthe events players face duringthe differentscenes in the game. Sincethe gameplayisimmensely affected by the requirements mentioned in Section3.1, the sectionabout gameplayalsocoversits relationtofulfilling these requirements. Thewayshow variousgame design elementsare integrated into the game are thenextfocal pointofthis chapter before concludingitwith the technical aspectsof the implementation.

4.2 Created Scenes in the Game

4.2.1 The Moon Scene The game’sstarting pointisincludedinthe moon scene which givesthe playerthe first impression of theenvironment. Other than acknowledging the purpose of theplaced objectsinthe virtualenvironment, it is essential to understandthe role of this part of the game, howitaffects the player’s experience overall, and howithelps with fulfilling at least some points of the previously listed design requirements.These aspectsshould be investigated forevery part of the moon scene in order to see howthey areplanned to influence the player.

The moon scene itself can be divided intotwo diﬀerentparts: The ﬁrst partiswhere

49 4. Implementation of Astroclimb

Figure 4.1: Across-sectionofthe hangar Figure 4.2: The massivespaceship that -the startingpointofthe game. bringsthe playertothe climbing wall.

the playerfinds themselves oncethey enter the game, thehangar of aspaceship.The second partiswhen the playermakes out of thespaceship and startsclimbing above a colonized moon. The hangar areaisalarge compartment(Figure 4.1) at thebottomof an immensespaceship (Figure 4.2) with some equipment lockers, an oxygen tank, some crates, and storage places. It alsohas ahuge blast door that opensand allowsthe player to leave the spaceship. Theobjects andthe textures chosen for theseobjects have a modern look and asci-fi feeling which can convince players thatthey are in aspaceship. Thisfirst impression is crucialbecause it is thefirst step to makeplayers believethat they are actuallypresentinaspace environment. If they canimmersethemselves in this scene theremainder of thegame will makemore sense to them although most of the aesthetics are designed unrealistically.The onlydisadvantage of this areaisthatthe wholecompartmentisnot traversable by the playerbecause of thephysical limitationsof the VR room setup. The player is only abletomove to the leftorrightinfrontofthe blast door besides being abletofreelyobservethe whole area.

Once the blast door opens, theplayerbecomes abletoaccessthe outer space by stepping on ahoverboardthat is waiting for them in frontofthe climbing wall. The hoverboard gives theplayertime to get ready for theclimbaswellasobservethe scenery surrounding them.The most noticeable objectsinthis scene are themoonbelow theplayerand the climbing wall ﬂoating in frontofthe player. Themoon’s surface is inspired by the Earth’s moon and has awhite-graycolor pattern. Thecolonization on themoonhas living hubs, transporters, communication satellites,acommand base, platforms, and mining vehicles. All of theseobjects’ colorpalette is heavily white-centric. The main purpose of picking a moon very similartoEarth’smoon, keepingthe type and thediversityofused objects notfar from reality,and focusing on white color is to giveplayers somethingsimilar and familiar to what humankindiscapable of doing in outer space rightnow and in possiblenear future. Thisfamiliarity canhelpplayers to get used to thescene faster by recognizing thefunctionalityofseen objectseasily and keep them immersive at all times. In comparisontothese familiar visual aesthetics,the climbing wall stands out as

50 4.2. Created Scenes in theGame an anomalyinouterspace. As previously mentionedinSection 3.2, theclimbing wall is made of amaterial that is fully transparent, so it does not blockapart of themoon and thespaceships thatﬂy, warp in and out as theplayerclimbs higher. Thespaceships thatappear throughout the game have heighttriggers where oncethe playerreaches certainheights on thewall they jointhe game. Whilethe purpose of theclimbing wall is self-explanatoryfor Astroclimb, themainreason behind the spaceship events is to keep thegame interestingand interruptthe routineclimbing activitywith some visual surprises. Once theplayerreachesacertainheightthe second main scenery comes in which is explainedinthe next subsection.

4.2.2 TheOwl Scene Astroclimbhas asingle transition pointwhich is handled in the owlscene. Similar to the moon scene mentionedinthe previoussubsection, this scene alsohas aspecial purpose in the gameplayand helps furtherfulﬁlling some of thedesignrequirements mentioned in Section3.1. Theremainder of this subsectionlooks into thesepointsand clariﬁes the goalsbehind applying thesepoints to the game.

The owlscenehas twomain tasks:

1. Acting as abridge betweenthe moon scene and theasteroidbeltscene.

2. Oﬀering the playerachoice whichaﬀectsthe gameplay dramatically.

Once the playerreaches acertain heightonthe climbing wall, theynotice thatitisnot possibletoclimbhigherinthe virtualenvironmentbecause thereisnowall to climb. However, they seethatanother part of theclimbing wall is bent backward as seenin Figure 4.4. Thiscertainheighttriggersthe abrupt change of thescene where everything but the climbingwall disappearsand thedarkness descends onlyallowingthe playerto see certainobjects. Oneofthe goal of this abrupt change in thescene is to catchthe playeroffguard and surprise them while planting curiosityintheir mindsabout whatis goingtohappen next.Anothergoal of this segment is forcingplayers to pause climbing forawhile as they figure out what is happening. Climbing can be an exhausting activity for inexperiencedclimbers, so givingplayers time to rest their bodies by justhanging up on thewall should helpwith reducingthe exhaustion thegame creates. Whilethe player is in this state anothersurpriseelementjoinsthe game: themechanical owldesignedto change the game flow.

The mechanical owl(Figure 4.3) is inspired by the owlstatue thatstands at thetop of thelibrary building of ViennaUniversityofTechnology.Itappears slightly behind theclimber’sleft sideand presents three transparentorbs forthe player. Theplayeris supposedtochoose one of theseorbs by touching them with theiravatarhand.The orb selection triggersthe changestothe glovesortothe climbing wall whichare explained in Section4.3.1.The structure of the designed owland the chosen texture makeit ﬁt into the sci-ﬁ style of thegame perfectly.The ideabehindcreatingthis harmony

51 4. Implementation of Astroclimb

Figure4.3: The mechanical owlde- Figure 4.4: The endofﬁrst segment in signedfor Astroclimb. the game.

with thedesign of elementsistohelpplayers with making sense of theenvironment with currentsettings.Awakening this feeling in players should directly translate into improving the immersivenessofthe artiﬁcial environmentfor them. Consideringthe odds of encounteringamechanical owlinouter space are close to zero, theappearance of the owlshould surprise the playerand make them curious about it.Moreover, the changes applied to theglovesorthe wall basedonthe player’s selection should trigger afeelingof satisfaction for players since theseobjects areconsidered the most valuable to them.The purposeofthese eventsistomakethe game more engagingfor players so they want to continueplayingthe game with more expectations.

Once the orb selection phase is completeand the corresponding changesare applied, the owldisappears. This endsthe owlscenesegmentand starts the asteroidbelt scenewhich is explainedinthe next subsection.

4.2.3 The Asteroid BeltScene Besides theclimbing section, the asteroidbeltscene alsoincludesthe endscenefor Astroclimb. The asteroidbeltscene setup has various purposes that satisfy thepreviously mentionedrequirements further. Theprimary objectives this scene tries to achieveare listed below:

1. Completing thescene transition that startswith ﬁnishingthe ﬁrst part of theclimb to give players afeeling of switching places in outer space.

2. Creating amore dynamic environmenttokeep players interested in the game.

3. Finding solutionsfor the problems that come with VR-relatedlimitations suchas playerspace and thephysical climbingwall’s capabilities.

52 4.2. Created Scenes in theGame

4. Givingplayers the chance to try out thechanges that happened withselecting an orb.

5. Creating an extrachallenge for players by tilting the wall forward.

The remaining of this subsectionlooks into theseobjectivesand howthey are achieved in the game.

The scene translation is easier in games where theplayercan move aroundthe environment. The objectsinsuchenvironments do notneedtobeadjusted abruptly. In gameslike Astroclimb, thespace providedtoplayers to move aroundislimited. Theclimbing aspect of thegame addsmore to theselimitations and keepsthe playeronthe wall at all times. The physicallyavailable space VR setup providesand the motionsickness aspect of VR takeawaythe ability to dynamicallytransitionscenesinAstroclimb. The designedspace forall Vreeclimber related games is approximately 4metersby2.5 meters. Considering players onlymoveonthe wall exceptfor theintro scene in Astroclimband climbing the wall is the main mechanic, they do not have toomuchfreedominterms of movement. Although thespace in the virtualenvironmentislimitless, moving the playeraround the outer space with thewall while theirbodyisnot moving in thereal world would cause motion sickness as explained in Section 2.2.7. Hence,changingthe scene abruptly while keepingthe most importantobjects, theclimbing wall and avatar hands, in place wasthe solution to preventmotion sickness and change thescene. The so-far in-game experience of sci-fi feelingwouldalso givethe playerthe toleranceand acceptance of suchunrealistic occurrences. Once theowl scene is completed,the environment changesbacktoouter space,however, this time everything is differentinthe scene.There is atotally different color of the nebula thatstatesthis new place is somewhere else. Themooncolony, the spaceships,and the floating hoverboard are gone.The majorobjects in the new scene consistofablackhole far belowthe climbing wall, andthe asteroidbeltwhichholdsthe climbing wall in the middle of it.The asteroids are floating back and forth as theplayer climbs up thewall.The main goal of thesechanges is to givethe playerafeeling of suspense and makethe game moreappealing to them.The increased dynamism during this part of thegame is addedtotakethe player’s attention from climbing occasionally and gaze upon thescene moreoften. Anotherreason behind this is again to slowdown the player’s climbing whichwouldalso helpwith reducingthe negativeeffectsofthe physical climbing wall’s limited speedexplained in Section3.4. Thereare other measures taken to helpwith this main issue of players’ climbing speed exceeding therotation speed of thephysical wall: Thechanges applied to theavatar handsand the virtualclimbing wall.

When theowl appears halfway through the game, it presents three diﬀerentorbs which include small representations of theoutcomes of picking them.Theseare animated representations thatpointout thesepossible outcomes:

1. The ﬁrst orb rendersone of theavatar handsinvisible randomly foracouple of

53 4. Implementation of Astroclimb

secondsand it occurs occasionally and repeatedly.This changes thegameplayfor the playerinaway thatthey have to make diﬀerentdecisions for therestofthe game. If theplayerdoesnot feel safe by notseeingone of theirtrackedhandsduring the game, they would want to wait until it is visible again to continueclimbing. Anotheroptionisguessing the position of theinvisible avatar handand still trying to hold onto aclimbinghold.

2. Choosing thesecond orb would duplicate the avatar hands and place them alittle farabove the avatar handsthat are trackedbyVIVE trackers. These copies mimic the rotations and translations of thereal avatar hands. Being abletoclimbwith four handsyields more points sincethe numberofhands touching the climbing holds is doubled.This option is considered for players thatfocus on scoringa highscorefor thegame. Controlling fourhandswouldalsobeconfusing for some players thatcan makethe climbmore challenging. Sincethe positioning of hands is more importantwith four hands, players can aim for the small gripswhichwould allow them to scoreevenhigherscores. The time spentbycritically thinking about choosingspeciﬁc climbing holds to gain morepointsshould alsoslowdownthe player’s climbingspeed.

3. The lastorb is ratheranalterationapplied to the virtualclimbing wall thanthe avatar hands. Selectingthis orb renderssome of theclimbing holds invisiblefor the remainderofthe game. Thisoption restrictsthe number of available climbing holds forplayers. This restrictionshould make thegame morechallenging and force players to think about howtoposition themselves on thewall better fora smooth climb.

The outcomes of selecting an orb are not theonly sourcefor making thegame more challenging and interesting. Tilting thewall forward is anotherchallenge players have to face in the game.

Once the playerreachesacertainheightinthe game amassive asteroid is launched from farawayinouter space. This asteroidslowly approachesthe upper side of the virtual wall and hits it whichresultsintilting the wall forwards. All this motion is perfectly mirrored with thephysicalclimbing wall. Thetilting of thewallcreates an additional physical challenge for players towardsthe end of the game.

Once the climbable part of thewall is over, theblack hole belowthe climbing wall sucks everything into itself exceptthe player. While the playerﬂoats in outer space an alien spaceshipsuddenlywarps in which indicates the end of thegame.The ending of the game should leave the playerwith mixedfeelings. The appearance of an alien spaceship mightworryorexcite players about what is goingtohappen to them. They might as well be disappointedinthe massivespaceship thatbroughtthem to the celestial climbing wall and didnot come backfor them. Ifthe game can rise suchfeelings in players, it meansthatthe game wasanimmersive experience forthem.

54 4.3. Gameplay and Atmosphere in theGame

Thissubsectionexplained the main scenesinAstroclimbwhile trying to not go into details about thegameplay.The next subsection gives moreinformationabout howthe gameplay is structuredand howthe atmosphere inthe game is created.

4.3Gameplayand Atmosphere in the Game

4.3.1 Game Chapters and Events The previoussubsection already informs about thegame flowbymentioning theenviron- mental design of thethree main scenes. The game, however, should be divided into parts differentlywhichincludes parts fromdifferentscenes. Eachofthese chaptersincludes various events thatpossess distinct influencesonthe game flowand game gameplay. It is crucial to understandthe reasoningbehindthese events in every single chapter and how they can affect players.

Astroclimbmainly consists of three chapterswhichcan be called the intro part, the climbing part, and theoutropart.The intro part starts with thegame and ends oncethe playertouchesthe first climbing hold on thewall. Sincethis segment is fairly short, there are onlyafew events happeninginthis part: Once the playerisout of thespaceship and on thehoverboard, the massivespaceship ascends slowlyand then warps out after reaching acertainspeed. Thisevent leaves the playeralone with the climbing wall, and the hoverboard they are standing on. The departure of the spaceshipalso unlocksalot morespace to look at that gives theplayerthe perfect time to look aroundand seewhat this outer space offers. Besides startingthe game, thefirstinteraction with aclimbing hold alsotriggersthe hoverboard to leave and makeitglide aroundthe climbing wall as the playerclimbs up. Theeventshappeninginthe intro chapter are pure aesthetics to makethe environmentcompelling for theplayer. Thefollowing climbing chapter includes similar events that improve visual aesthetics as well as events that impactthe gameplay.

Once the playerstarts climbing,various events occuruntil the end chapter of thegame. The first events consistofspaceshipswarping in andout,and having pursuits on each other.The goal behind thesepurely visual aesthetics-related events is to preventthe game from becoming dull andmakeplayers takeamomentbygiving them something to observe as they climb. As previously mentionedinSection 4.2, theorb selection phase thatcomes with themechanical owlformsthe importantevent thatimpactsthe gameplay. Buildinguponthe already existed mechanics, being abletotouchthe climbing holds with avatar hands and gain points in this case, should giveplayers afeeling of progression and something to look forward to forother possibilities.The main purpose of changing and improving the wayplayers cangain points, and thedifferentdistributionof climbing holdsonthe wall is to keep the gameplayand game flowdynamic.Keeping the dynamism in the game should force players to react to changesand adaptaccordingly. As players trytoadapt to the changesafter the owl’s visit, the next importantevent is the crashing of an enormousasteroidtothe climbing wall. If the playerpaysenough attention, it is possibletosee this asteroid slowly making its way to the upper side of

55 4. Implementation of Astroclimb

the wall. Noticing this before the crash would make the playernervous and maybestop climbing for amomentthinking thatitmighthit them.When the crash happens,the eventchanges the game ﬂowaswellassome visualsinthe environment. On the one hand,asmentioned in Section 4.2, thetilting of thewall challengesplayers physically. On the other hand, thecrashdestroys apart of theupper wall whichcauses manywall fragments to spread into outer space.Since climbing atilted wall canbevery challenging for some players,this eventisput towardsthe end of thegame.

The lastevent occursatthe end of thegame as theblackhole sucks everything but the playerinand an alien spaceshiparrives.Takingaway the climbing wall from theplayer shouldsignal the playerthe end of theclimb and therefore the end of the game.

The next subsection goes moreintodetailabout gameplayand explainshow scoring works and changesthroughout the game, and what other information suchasatimer and aheightindicator isthere forplayers.

4.3.2 Score, Timer,and Height Indicators Astroclimbpossesses various indicators attachedtothe lowersideofthe avatarhand models as seeninFigure 4.5. These indicators help with creatingthe gameplayfor Astroclimband induce distinct game design elementsintothe game. Thissubsection informs about howtheseindicators work and howthey contribute to the requirements explained in Section 3.1. Scoring in Astroclimbisachieved by interactingwith climbing

Figure 4.5: Time and heightindicators are placed on the leftavatarhand,while the score is on theright avatarhand.

holds.Theseclimbing holds are worth 10 points if theirsize is consideredlarge,20if they are small. If theplayeralready touched aclimbing hold, its color changestogreen indicating thatthis climbing hold is marked, andtouching it again will not issueany additional points. In order to preventplayers interact with many climbing holds in quick successionstoabuse thepointing system, the following measure is taken: The playerhas to stayincontactwith the climbing gripfor at least 1,5 secondsand the points apply

56 4.3. Gameplay and Atmosphere in theGame oncethat climbing hold’scolor turnsintogreen. Thissums up the basics forthe scoring system, however, the scoring changesfor most casesasfollowing oncethe playerselects an orb:

1. If theorb thatduplicates the avatar hands is chosen thescoringsystem stays the same,however,the copies of avatar hands are alsoable to score points if they come in contact with climbingholds.

2. If theorb thatmakes one of theavatarhands randomlyinvisible ischosen,the scoringsystem rewardsthe playerbydoubling thepoint gain for each climbing hold thatistouchedbyaninvisible avatar hand.

3. If theorb thatrenders some of the climbing holdsinvisible is chosen,the pointgain for everysingle climbinghold is doubled.

The alterations made in thescoringsystem after selecting an orb are to balance the game in termsofscoringasfairlyaspossible.The orb choice for players thatfocus on scoringhigh scores would be the third orb explained above sincethat choice doubles the pointgain in all cases. Instead of scoringhigh points,ifplayers focusoncompleting the game as quicklyaspossibletoget agoodtime score,the game provides atimer forelapsed climbing time.The timerstarts as the playertouchesaclimbing hold and ends oncethe playerreachesthe very end of theclimbing wall. Players thatfocus on achievingashortclimbing time wouldbenefitmore by picking thefirst orb option listed above.Occasionally not being abletosee theavatarhandsand aclimbing wall with missingclimbing holds might causeplayers to stall and thinkabout theirnextsteps longer thanusual. Besides providing challenging and competitive gameplay,the timer and thescoreindicators also aim to reach players with differentpreferences to createa diverse gameplayerbase.

Unlike score and timer indicators, the heightindicator is added onlytogiveinteresting statisticstoplayers. Thenumberonthis indicatorchangeasthe playerclimbs higher on the wall. This piece of information is available to the playeratall timesjust by looking at their left avatarhand.

The next subsection switches from gameplayand mechanics to building thevisual aesthetics that create thesci-ﬁatmosphere in thegame.

4.3.3Modeling andUse of Game-readyAssets

Astroclimbuses amixture of many self-modeled and game-readyassets that createan outer space atmospherewith sci-fi elements in it. These elementsdirectly improve the visual aesthetics of thegame.The remainder of this subsectioninforms about theobjects and areas designedfor theartificialspace scene and where theinspiration comesfromfor usingthese specificobjects.

57 4. Implementation of Astroclimb

Figure 4.6: An early design stage of Figure 4.7: The hoverboard designed for players the mechanical owlinBlender. to stand up on before the climb.

One of theinitialsteps to createthisouter space wasbuilding the skybox forthe environmentinUnity. Forthe first part of theclimbing,anebulawith lightcolors that include green and blue is chosen to giveplayers afeelingofrelaxation. In contrast to this choice forthe asteroid belt scene,ared-heavy nebulawas chosentosignal thedangerof the objectsinthe scenery.One of thefirst objectsspecifically designedfor thescene was the hoverboard seeninFigure 4.7. Blender [15]isused for modeling this objectwhichis then textured with Vreeclimber’s logo and colored with matching colorstothe nebula’s blue &green. Theidea of using ahoverboard is inspired by the movie series Back to the Future [65].

The mechanical owlisanotherobjectdesignedspeciﬁcally for thegame by using Blender again.Figure 4.6 shows an earlymesh versionofitinBlender. Thetexturesare provided by freeonlineresources.Shinytexturesare usedfor theowl to make it stand out in the dark.

The moon colony(Figure 4.8) is one of thelargest objectsinthe game, consisting of manyself-designedand modeled objectsand game-ready3DassetsprovidedbyNASA [111]. The terrainofthe moon ismade by Unity’s oﬃcial terrain tool to create an areafor thecolony. Thiscolonyarea includesliving hubs forastronauts, debristhat shows unsuccessful attempts of thefolk on themoon, structures they buildsuchasgiant communication satellites, acommand center, spaceship launcher platforms,and mining equipment.Theseobjects areplacedinamanner so that they can givethe impression of acolonytothe player.

The spaceships (Figure 4.10) used in Astroclimbare free assets, including destroyers and TIE ﬁghters from Star Wars series [67], and Vipersfrom the Battlestar Galactica [64] TV show. Thegoal behind using known spaceships fromsuccessful TV shows and movie

58 4.3. Gameplay and Atmosphere in theGame

Figure 4.8: The moon scene. Figure 4.9: The asteroidbelt scene.

Figure 4.10: From left to right: The destroyer, Viper,TIE ﬁghter. series is to createasurprise eﬀectfor players when they seethem in the game.

The asteroids in theasteroidbeltscene (Figure 4.9) are taken from Unity’s assetstore and stored as prefabs in Unity.The algorithm that creates theasteroidbeltpicks one of theseprefabs randomly, adds arandom velocityand tumble rotationtoit, and sends it throughthe outer space towards the climbing wall. Dozens of theseasteroids are launchedatthe same timewhichcreates theasteroid belt.The other mention-worthy object in theasteroidbelt scene is the black hole (Figure 4.9) which is created by using the particle system in Unity.The purpose of placing theblackholebelowthe climbing wall is to encourage players to climbhigher up.

The use of these objectscreated satisfactory outer space scenesthatﬁtthe concept of Astroclimb. Besides visual aesthetics,background music andsoundeﬀectsalso improved the aesthetics of thegame which are explained in the nextsubsection.

4.3.4Music and Sound Effects One of themost influential aesthetics typesthatimproveimmersion overallisaudio. Astroclimbprovidesthis kind of aesthetics in differentwayssuchasplaying musicin the background at all times and supporting events with sound effects. Thissubsection

59 4. Implementation of Astroclimb

investigates thereasoning behind choosing multiple background music tracks and playing sound eﬀectsincertainsituations.

Background music is the mostnoticeableauditory aestheticofAstroclimbthatchanges overtime duringthe game. As previously mentionedinSection 4.3.1, thegame is divided into threemainchapters thatreflectthe game states theplayercan be in. Forthe intro part, acountry-western songcalled Benson Arizona [185]performedbyJohn Yager is picked. Thesong’srelaxing tuneswereconsidered an adequatefittoget theplayerready for the climb. It is alsoone of thesoundtracksfromthe movie Dark Star[66]whichisan old American science fiction comedyinwhichthe story involves funnyeventsinouter space.The next background music that follows Benson Arizona is Echoes [186]byPink Floyd. This song is purelyinstrumental at most parts and has afairly slowpace at the start.Since Astroclimbonly usesthe first three minutes of this trackatmost,this makes the song afine fit forthe longest part of thegame. The idea behind picking this song was to keep theplayerfocusedonthe climbing and theeventsthat occur at certainstages of the game. In comparison to Echoes, Mr.Spaceman[187]byThe Byrds, whichisused for theoutro scene,isafast-pacedsong with the genreofcountry-rock. It wasplanned that this dramatic change of tuneswouldcreate awake-upeffect on theplayerand signals the endofthe game. Sciencefiction and space are thecommon themes in thesesongs.The useofBenson Arizona in ascience fiction movie, Echoes evoking an outerspace feeling with itsmelody, and Mr. Spaceman including lyricsthat describealienscreate theirown relationships to thesethemes. Besides thesebackground music tracks, theowl phase alsohas aspecial background sound which can be described as static noises.The goal behind this change is to givethe playerafeeling of being somewhere unexpected suchas in-between dimensions. Jiulin Zhangetal. also pointout the importanceofbackground music in videogamesfor increasingimmersion [41], however, it is not the onlysource for auditory aesthetics.Sound effects areanother sourcethat complements them to increase the immersionlevel inthe game.

SinceAstroclimbtakes place in outer space,logicallyitdoesnot makesense if someone hears noises or sound effectsinsuchascenario, however, excluding sound effectsfrom a digitalgame would cause aless immersiveexperience [135]. In Astroclimb, sound effects are assignedtoimportanteventsthathappen throughoutthe game. Here is alist of some of these events that aresupported with auditory feedback:

•When the hangar door opens at thestart of the game

• When themassivespaceship thatbringsthe playertothe climbing location in the game leaves

•When spaceships warp in and out

•When the playerscorespoints by using aclimbing hold

•When an orb is selected and thechanges are applied in the scene

60 4.4. Technical Aspects

•When the second part of thewall straightens up after theowl phase

•When the largeasteroidhits the wall and apart of thewall breaksintopieces With the addition of thebackground music tracks and various sound eﬀects, Astroclimb aimed to improve the immersion level of the game and provideabetter experience to players. This subsectionﬁnalizes the conceptionofthe game in termsofgameplay and game atmosphere.The technical aspectsofthe game suchasthe implemented core scriptsand howthese scripts ensure the gameplay are explained in thenext subsection.

4.4Technical Aspects

4.4.1CalibrationProcess Astroclimb’score template consists of scriptsthat enable the climbing logic in thegame. These scripts are responsible forcalibrating the scene by aligning thephysical objects with theirvirtualrepresentationsand keepingthem aligned at all timesthroughout the game. There are two distinct calibration processes thatmakeclimbing in the virtual environmentpossible: 1. Calibration of avatar hands and feet

2. Calibration of theclimbing wall Calibration of theavatarhandsand feet starts with finding the correct VIVE Trackers in the environmentwith the helpofTrackerIdentifier.cs script.Then, AvatarCalibration.cs orients thehand and feet avatarstowards thewall plane.Inorder to achievethis, the hand and feet avatarsare rotated aroundall three axes until the avatars’ wall-facing and ground-facing planes are orientedtowards thepredefinedwall and groundplaneinthe game. With thehelp of thesescripts, players are abletouse theirhandsinthe virtual environmenttointeract with objectswithout suffering from anynonalignmentissues. Thiscalibration process is crucial duetothe fact thatitenables players to use their handsaccordinglywithout breakingthe immersion. Besideshand and feet calibration, climbing inAstroclimb alsorequires aperfectalignmentofthe physicalwall.

The wall calibration process consists of two parts:The initialcalibration and theongoing calibration during thegame.The initialcalibration process is accomplishedmainlyby the SceneCalibrator.cs script. First,the script tries to findawall trackeronthe right side of thewall andanother oneonthe leftside. Once thesetwo trackers are found, the program needstofigureout whichpair of trackers are found, as thereare fourpossible combinationsofwall trackers. Therefore, the verticaldistance between both trackers as well as theirhorizontal positions is usedfor theidentification.After the identification, the VR environmentisshiftedalongthe x- and z-axis depending on theposition of the identified trackerand its corresponding position on thevirtualboard.Then,the climbing holds are shifted alongthe y-axis depending on theverticaldifferencebetween the trackerand the predefined position of thetrackeronthe virtualwall.This series

61 4. Implementation of Astroclimb

of processestakeplace at thebeginning of thegame,however, in order to keep the climbing holds aligned,additionalmeasures have to be taken due to the rotationofthe physical wall. CorrectVerticalError.cs and CameraShift.cs are responsible for this task. CameraShift.cs movesthe VR environmentupwards whilethe physical wall is rotating. It alsoadjusts the speed of this movementwhenever the speed of the physical wall’s rotationischanged. Theupward movementisimplementedbyincreasingthe velocity of theVRenvironment’s Rigidbody in its local y-Direction. CorrectVerticalError.cs has hardcoded upward movementspeedsfor theVRenvironment. Although thesespeeds are very close to the physical wall’s rotationspeeds of diﬀerentlevels, they do not exactly match theactual speed of thephysical wall’s rotation. Therefore, in time avertical oﬀset between thehands&feet and theclimbing holds appears. Thisscript is responsible for compensating for this loss in accuracy.

Although thevirtualenvironmentisslowly shifting upwards in the game, this slowbut steady shiftingisnot noticed by anytesters due to their focus being on somewhere else at all times. With the combination of thesecalibration processes, the climbing experience does not breakimmersion in Astroclimb. Besides climbing-orientedscripts, thereare, of course,scripts that enablethe gameplay. Thenextsubsectionexplains some of these scripts.

4.4.2 Scripts The scripts used to manage thelogic in thegame can be divided into twodiﬀerent types: The scriptsthat are tightly coupled to eachother and react to game state changes handled in other scripts, and scriptsthat are mostly independent of theeventshappening throughout the game.

Scripts suchasGameplayController.cs thatisresponsible for dictating the game’scurrent state, MusicController.cs which changesthe music playing in the background based on the game’sstate, MilestoneController.cs that sets the second stage during the climbing part of thegame by changing theenvironmentand enabling the second part of the climbing wall are dependenttoeachother. The triggersthatchangethese game states are based on theplayer’s players movements and position. As an example,touching aclimbing hold changesthe game state from intro to climbing.Sincethe game is a sequenceofeventsand each small change that is supposed to happen, hastriggers, the order of theeventsisregulated by using one of Unity’s scriptingconcepts called Coroutines [171]and supported by boolean valuestocontrol theirrepetitiveness.Other thanscripts thatcontrol thegeneral ﬂowofthe game, thereare alsomultiple scripts that areresponsible for dictatingthe outcomes of certainevents. These scripts work in harmonytobeable to createthe desired logic. OwlController.cs, ManipulateFirstOrb.cs, ManipulateSecondOrb.cs, and ManipulateThirdOrb.cs together handlethe owl’s and itsorbs’ animations once theplayerreachesacertainheightonthe climbing wall. In addition to thesescripts, ChoiceManipulator.cs prepares the events dependentonthe chosen orb whichincludesmaking changes to the avatar hands and thewall’s climbing

62 4.4. Technical Aspects holds. WarningController.cs is anotherhighly-dependentscript that needstoknowthe currentheightofthe playeronthe wall all thetime so it candisplayawarningtextto the playerstating thatthe playershould pauseclimbing if the playergetstoo close to the upper side of the physical wall. These scripts are some of thecore building blocks for the logic of thegame, however, the game alsoconsistsofsome semi-independent scripts.

The semi-independent scriptsonly get informed about the state of thegame onceand handle the logic accordingly. BlinkBlink.cs thatisresponsiblefor making certainlight sources of themassive spaceship blink, and Asteroidshower.cs thatspawnsdiﬀerent types of asteroids towards the wall’s directionare good examples for this type of script. The combination of thesescripts and thecore onescreate the game logicthatcreates an essential partofthe Astroclimbexperience.

5 CHAPTER

Evaluation

Thissection covers the evaluation of thepreviously described implementation.Itstarts with goingintodetails about howthe setup is done to createanappropriate testbed for the evaluation. The Covid-19 measures forms thesecondpart as they were crucialto enablethe evaluation and testinginthe ﬁrst place.Then the wayhow the testingis handled composes the next subsection. Finally,the results are evaluated anddiscussed further. Theevaluation methods include answering questionnaires, one before and one after thetest session,observation,and an optional shortunstructuredinterview after the test.

5.1 Setup

As mentionedbeforeinSection 1.2, theimplementation wasbuilt upon theVreeclimber project. Thewall is 4.6m high that consists of acombination of 28 wide blockrowswhich hold atotal of 238 climbing grips and 4VIVE Trackers. As seeninFigure 5.1 of arow block,eachrow contains 8or9climbing holds.The arrangementoftheseclimbing holds on thewall is done in away thatthe whole mappingofgrips canresembleabouldering experience.The wall canrolldownwards with amaximumspeed of 4.78m/min which can simulateendlessclimbing.Furthermore,the wall cantilt up to 20° to createthe feeling of an overhanging cliﬀ.The whole systemdoesnot producenoisebeyond 68 decibels in good condition1.During the evaluation,all described featuresofthis rotatingwall playedacentralrole in theoutcome.

Additionally,strict safety measures were taken. Theparticipants had to wear asuit with safetyropes attachedtoit. As seeninFigure 5.2, an operator had thedutyofholdingthe climber’s ropestoprevent unwanted accidents. The sportsmat on theﬂoorisafurther

1The inner partsofthe wall need to be oiled regularly to keep the noise at desired levels.

65 5. Evaluation

Figure 5.1: The Vreeclimberwall.

measure to preventorreducethe eﬀect of possible injuriesincase of aparticipant’sfall. Participantsalso hadtowearclimbingshoes thatare designedfor bouldering.

Because of theworn HTC VIVE Headset during theclimb, various adjustments had to be made to thesafety ropeswithout compromisingsafety.Inaregular climbing scenario, asafety suite hascarabiners to attachthe safety rope to whichthen goes up at the front of theclimber(Figure 5.2). If the same concept waskeptfor climbing in VR, the front ropes would interfere with the VR headset.Thatwould be undesired because of safety, immersion,and tracking reasons. To preventthis fromhappeningarobust bar is attachedbetween thetwo ropescoming from thefrontside of thecarabiners. (Figure 5.4) These adjustments kept theropes from touching theVRheadset.

As mentionedbeforeinSection 3.1, thesuccess rate of tracking has adirectand immense effect on immersion. Placing theVRequipmentbased on needs wasanother important part of thesetup. 4lighthousesand 8VIVE Trackers are used for this mattertominimize anypossibletracking issues. Thelighthouses are used to trackthe position of theheadset, controllers, and trackers inside theChaperonarea [155]. Forthe best possibletracking experience,VIVE Trackers and theVRheadset should be visible to multiple lighthouses simultaneously.Toenablethis scenario,2ofthe VIVE Trackers are placedonthe dorsal sideofhands, and 2onthe dorsal sideoffeet. Although theseplacements of VIVE Trackers are on pointinterms of tracking limbsaccordingly, the tracking of theseVIVE Trackers becomesdifficult if the lighthouses are placed improperly.Figures 5.5 and 5.6 showpossible positions of theVIVE Trackers on thelimbs duringthe climb. In these cases, theVIVE Trackers find themselves in-between two solid objects, hands/feet,and

66 5.1. Setup

Figure 5.2: Operator holding the Figure 5.3: Carabiners with the climber. safetyropes. the wall. To alwayskeep thesetrackers trackable, variousroomsetups with diﬀerent positioning of lighthouses are tested. After comparing theresults of thesetests, twoof the lighthouses are placed at the lowand middle levels of thewall and close to thewall. The other 2lighthouses are positioned far backfromthe climbing wall at upperlevels which are mainly responsiblefor tracking the4trackers on thewall. These placements alsogot approvedbyProf. Kaufmann whospecializesinthe Augmentedand Virtual Realityresearcharea.

Figure 5.4: Extrasafetymeasureswith ropesand arobust bar.

There are two reasons behind using 4VIVE Trackers forthe climbing wall:

Calibrationprocess: The application startswith acalibration process where two VIVE Trackers must be presentonthe front side of thewall simultaneously.With the helpofthe calibration process,the physical climbing holds on thewall align with their virtual representations in theapplication.

67 5. Evaluation

Figure 5.5: Trackerishiddenbe- Figure 5.6: Trackerishiddenbe- tween thebodyand the wall. tween the hand and thewall.

Ongoingaligningprocess: As thewall rotates,the climbing holds stayalignedwith the helpofanalgorithm that needs at least aVIVE Trackergetting trackedinthe Chaperon area.

Because of thenumberofgrip blocks, theuse of at least 4VIVE Trackers on theclimbing wall is required to be abletoachieve thesegoals. Besides theoverall aligningprocesses, furtherin-game measures are taken in order to keep theclimbersafe and thetracking as smooth as possible, and increasethe feeling of immersion: In-game trackercovers: As trackercovers, spheres with dangerouslylookingelectrical circuits are placedwherethe VIVE Trackers on thephysical wall are supposed to be. The pure purpose of making thesevirtualrepresentationslookalarming is to discourage the climberfromtouching or holding onto theVIVE Trackers becauseapplying force on this fragile equipmentorcovering thesetrackersatany pointduringthe runtime of theapplication mayresult in reducing thequalityoftracking and as well as thelevel of immersion drastically.

Warning text: The climberiskeptataso-called climbing windowduring the climb which means that theclimberisrestricted to not climb toohigh up on thephysical wall because of safetyreasons. Exceedingthis highthreshold results in givingthe climber visualfeedbackwith awarning sound to make them pause climbing foralittle bit.

Skipping to end: It is possiblefor theclimbertonot want to continue with the content or with the climbitself because of various reasons.For that matter, aUIbutton is added to thegame that is onlyavailable forthe operator presentatthe PC.Pressing this button will ﬁnishthe simulation and jumptothe end screen of thegame.

68 5.2. Covid-19 measures

Shoeand glove size: 3diﬀerentvirtualglovesand shoesizesare available for the climbertopickfromatthe start of thegame so theirreal handand shoesizes can match with thevirtualrepresentationsasclosely as possible.

All thepointsmentionedabove created the setupfor asafe and immersive experience.

5.2 Covid-19 measures

Sincethe testingrequiresthe use of therotatingwall, operators and participants had to be presentatthe workshop. ACovid-19 procedure is prepared to minimize therisk of infection during the timespent in the workshop. Belowisthe list of taken measures:

• Participantsand operatorsmust be testedfor Covid-19 and theresults must be negative.

•Amaximumof4peoplecan be presentinthe workshopatthe same time.

• Participantsand operators must wear FFP2-maskstobeable to enter theworkshop. Sincethe test sessionswill takeplace insideofTUWien campus, all campus rules apply during entering and leaving the building.Afulllist of additional measures can be readonthe oﬃcial pages [182].

•Participants must keep theirFFP2-masksduring the climb.

• Participantsmust use the providedhand sanitizers before and after theclimband the test session.

•The providedclimbingshoes must get disinfected after use.

• The VR equipment must getdisinfectedbeforeeachclimb by the operators.Op- erators will wear plastic glovesduring the sanitization process and anew pair of gloveswill be usedbetween eachclimb.

All themeasures listed abovewere followed strictly.

5.3 Testing

The currentsituationthe world is in because of theCovid-19 pandemic and therequire- mentofbeing presentinthe workshoptobeabletoparticipateinthe study caused alow participationratethanexpected.Furthermore, it alsoaﬀected the diversityof the participantsinanegativeway.All participantswere males, but they hadadiverse climbing, VR, and gamingexperience,and age spectrum. Fordetailedbackground information aboutthe participants, thefollowing table is provided.

69 5. Evaluation

Age SexVRExperienceClimbing GaminghoursGaming hours Experience perweek for VR perweek 22 male3 23-6 1 27 male5 23-6 0 32 male4 30 0 47 male3 51-3 <1 31 male2 33-6 0

Table 5.1: Background information about participants

The test beginswith followingthe Covid-19measures.After fillingthe pre-questionnaire, the participant getsreadyfor thegame by wearing thenecessaryequipment and listening to the briefing.Once the calibration forthe wall, hands, and feet is done,the participant is ready to playthe game. After thegame, theparticipantremovesthe VR equipment,fills out theafter-questionnaire,and has asmallinterviewwiththe tester. Foramore detailed step-by-step walkthrough of this procedure please read Step-by-step Test Procedure in the appendix.

Approximately 30-40 minutes got reservedfor eachsession and theplanned time was enough for every test person. Thetestsessionswentmostly smooth in termsoftiming apart fromthe ﬁrst participant. There were some technical problems regardingthe wall calibration process,but the issue got resolved in ashort time.

Besides this smalldelay,there were acouple of further problems with thecomfortof some of theclimbers. The assembled hand-straps thatweredesigned for holding the VIVE Trackers on thehandsgot uncomfortable towards the end of theclimbing.One of the test persons alsoreported that therewas aslightoﬀset between theirleft hand and itsvirtual representation which made reaching thegripsnot as precise as planned.

5.4Results

The questionnairesanswered by the participantscreated amix of qualitative and quan- titativedata. Sincemost of thequestions thatgrade diﬀerentaspects of thegame are followedupbypersonal comments,the answers to most of thequestions willbehandled separatelyand include citations fromthe participantsabout theirthoughtstowardstheir experience.Figure 5.7 shows the eﬀect of various elements used in the game to increase the immersionlevels.

5.4.1 Immersion, Aesthetics, andStory Aestheticsare one of thecore game design elements that have the most direct relationship to aplayer’s experience.They must makesense to players so they canrelate events and objectstothe environmentthey ﬁnd themselves in. If theseelements seem logical

70 5.4. Results

Figure5.7: Eﬀectsofdiﬀerent game design elementsonimmersion.

to them forthe environment, players canimmerse themselves easily.Figure5.7 states thatthe use of aesthetics wassuccessful(See Section 5.4 for evaluation results),and this game design aspect waswell applied.The design of theenvironmenthelpedthe players a great deal with immersingthemselves and feel like apart of theenvironment. One of the participantsmentionedinhis comments: “In thebeginning,the door and theinteriorof the space station were realistically designed. Thisgave me astrong feeling of immersion right away.” Another participantmentionedthatthe launching of thespaceship, the surroundings in general,the background music, and thetransitionfrom the spaceship to the wall were particularly immersing.Soundeﬀectsare alsocountedasapart of aesthetics.Maybe notassuccessfulasthe objectsincludedinthe environmentbut the sound eﬀects aided to enhance immersion.

In comparison to environmental elementsand sound effects, thestory had alesser impact to increase the immersion,however, as thegraph states, it still contributedtogiving a moreimmersiveexperience. Thestory wasaprelude to the main eventinthe game and tried to setthe stage for theplayerbefore experiencingthe VR environment. Feeling immersedwith both of thesegame design aspectsalso means that theconnection between aesthetics and story wassuccessful. Thestory shortly states thatthe playerisinaspace odyssey and makes apit-stop to climbananomaly wall. This small piece of information gives theplayerwhat kind of environmenttoexpect once he wearsthe VR glasses. The startingpointwhichisthe hangerofanenormous spaceshipconfirms thestory forthe playerand then seeing the climbing wall forthe first time supportsthis story further. These elementsshould complementeachother to make players feelmore immersed in the scene.

71 5. Evaluation

The existence of anon-playablebut interactable character in thegame gave controver- sial feelings regardingadding more immersion to the experience.Almosthalfofthe participantsstatedthatthe owldid nothelpwith increasingimmersion levels at all while theotherhalf feltthe effectsofittoagreatextent. One of theparticipants that did notfind the owlimmersivereported that it waslacking realism because an owlis unnatural both in climbing and space. Anotherone acknowledged that he recognized the owllate because it waskind of behind him and pointed out that aclimberalmost alwayslooks towards the wall instead of checking thefrontview. Thehigh experience of theseparticipants in climbing and theirlow to nonegaming habitscan be thereasons behind their interpretations. It is possiblethatthe expectationsfrom agame can differ on an individual level. However, none of theseparticipants reported thatthe existenceof the owlwas immersion breaking. Thisresultcan be explained with Cheng and Cairns study [22]. Theyexamine in their studyhow agame should behave and what would happen if thatbehaviour wasdeliberatelymade to be incoherent. The resultssuggest thatimmersion within an application can overcome effectsthatare completelyagainst userexpectations. Other participants reportedthatthe interactionwith the owlwas greatly immersiveand one of themost memorableeventsthroughoutthe game.

The occasionally appearing verticaloﬀset betweenthe hands and the virtual gloves, the need for rearranging of headphones during the climb, the wait to continue climbing because of thepreviously mentioned safetyreasons were reported as immersion-breaking parts during the climb.

5.4.2 Fun, Tiredness,and Motion Sickness

Funisone of the most iconic game design elementsagame needstopossess.Figure 5.8 showshow engagingthe participantsfind the game. It affirms thatall participants enjoyedtheirexperience greatly. However, this is justageneral statement from the participantswhichdoesnot informthe game designer about thespecifics of theparts that made thegame enjoyable,hence theparticipants were alsoasked about whythey findthe game engaging. Oneofthe participantsreported that thegame wasunique while anotherone found the general idea and thedesign behind the game neat. Another participantfoundthe idea of being abletoclimbinfinitely appealing. The combination of physical climbing with aspace-themed VR environmentthat offers differentlevels and being abletoexplore the environmenttoanextentwerethe aspects for aparticipant thatmade thegame fun.

As explained previously in Section 4.3.1, theplayerisgiven achoicethrough the middleof the game which aﬀectsthe rest of the climbremarkably.AsseeninFigure 5.9, participants found thatchange in theﬂow of thegame (more) challenging or/andengaging. One participant reported thathemisinterpreted the goal.

Furthermore, most of theparticipants reported that they would notbeinterestedin playing asimilar game on aPC. Oneofthe participantsbelieves thatphysical climbing

72 5.4. Results

Figure5.8: Eﬀectiveness of some of thein-game experiences.

Figure 5.9: Eﬀectsofthe chosen orb on thegame experience. is essentialinsuchasetupand thecontrols on aPCgame would make the game boring. Another participantthinksthatexperiencingsuchanenvironmentinVRisthe most interesting aspect of it and theway youcan immerse yourself when physical activityis at presentisunique. These comments indicatethat it is more desirable and makesmore sense to participants to play agame that involves physical activityinaVRenvironment.

73 5. Evaluation

Amention-worthyﬁnd is thatthe participantsdescribed the game as relativelytiring as seeninFigure 5.8. Thiswas mentionedmultiple times duringthe short interviews after theclimbs as well. Whenthe speciﬁc part asked about thetiring part of theclimb, participantspointedout the time towards the end. Towards the end of theclimb, an asteroidcrashes the top sideofthe wall which triggers the physical wall to tilt forward. Thismeansthat the participantsclimbedatleast aquarterofthe wall while it wastilted which required more force to hold onto climbing holds.Considering no one quit climbing during the test, this tells thatthe enjoymentthe players received took over thetiredness.

Figure 5.8 shows that there were not anymotionsickness complaintsfromthe participants during or after thegame which is agood sign. Thispiece of information indicates that the decisions made while designing the game helped with preventing possiblemotion sickness cases. Thiscan alsobeexplained thatall of theparticipants had VR experience before and are used to thesituation.AsAlex Riviere mentionsinhis blog[133], some game developers intend to saythat with experience of hours playing in VR, peopleeventually get used to it,and the problemofmotion sickness willberesolved on itsown with time.

5.4.3Problem Solving, Critical Thinking, andReplayability

As previously explained in Section 4.3.1, the player hastomakeachoicebetween three presented orbstobeable to continue climbing.Althoughthe orbsare animated and eachofthem gives hintsabout howthe glovesget enchanted, thesituation wasstillnot perfectlyclear to theplayer. The purpose of this section of thegame is to force players to think critically and guess thechanges that will be applied oncethe climbcontinues. On one hand, as seeninFigure 5.10, theparticipants found theidea of theseenchantments fairly interesting.Onthe other hand, figuring out thechanges thatwill be applied for the rest of thegamewas fairlydifficult. Twoofthe participants reportedthat they did not think about theoutcome and randomlychose one of theorbs. One of theparticipants stated thathechosethe middle orb because he wassure what wasgoingtohappen if thatorb would be chosen.Anotherparticipantfigured out thepossible outcomes of every choice and chose theone thatseemed themost challengingamongst them. Moreover, a participant addressedthatone of theanimationswas misleadingbecause no onewould expect theglovestoget duplicated.Anotherparticipantreported that he misinterpreted the same animation and thoughtpicking thatorb would specify whichgrips to hold as next.

Makingparticipants misinterpretthings inthe game can be seenasadesign issue, however, misinterpretations buildthe path to solvepuzzles.The main goal is actually achieved herebymaking some of theparticipants guess things wrong.

Although thechoices were generallyunclear and relativelyhard to understandall participants managedtounderstand thatthey hadtopickanorb to be abletocontinue climbing. Thisbehaviour states that they were abletosolve the problemthat wasthrown at them.

74 5.4. Results

Figure5.10: Participants’ thoughts on orbs.

After theclimbing sessionendedfor one of theparticipants,hewas curiousabout what would happen if he pickedone of thetwo other orbs. Explaining theoutcomes made him interested enoughtoplaythe game again and this time he pickedanotherorb once that stage is reachedinthe game. He reported after hissecond climbthatheenjoyedhow differentlypicking another orb affected the outcome of the climb. Thisbehaviour shows curiosity leads to the replayabilityofthe game which is anotherimportantgame design element.Figure 5.11shows howlikely it is forthe participantstoplayagain to see the other presentedoptions would affect their experiences. Besides curiosity, there are other aspectssuchaschallenging other players that can lead players to replay the game. All participantsagree with this statementand as seeninFigure 5.11, everyone is eager to playthe game again to beat their ownoranother player’s score or time.

5.4.4ElementofSurprise, Curiosity, and Progression One waytokeep players interested in thegame they are playing is by creatingsurprises and unexpected events. All participants experiencedatleastamomentwherethey were surprised.Threeofthe participantsfoundthe appearance of theowl andthe options it presentssurprising.Anotherparticipantreported that theasteroid hittingthe wall which makes apart of theglass wall shatter caught himoﬀguard.The hangar door’s openingand seeing the space environmentfor theﬁrst time wassurprising foranother participant.One of theparticipants reported furtherthat noticing howhigh he climbed after lookingdownsurprisedhim.

After theclimb, the participantswere alsoasked whether they feltthe physical wall getting tilted at onepoint during the game. Mostofthe participantswere baﬄedby

75 5. Evaluation

Figure 5.11: Likeliness to playthe game again.

the questionbecausenone of them noticed that thewall they were attachedtoactually tilted forward.Anotherimportantacknowledgmentwas that noneofthem feltthe wall wasrotatingalthough they knew thatishow thewall operates. Theseobservationscan be explainedbyhow highlyimmersed theparticipants were in the game.

Curiosity is anotherway to makeagame appealing. Aparticipantreported that the very beginning of thegame where he waited forthe door to open made himcurious about what is behind the door. Anothersource of curiosity wasthe owland the possible outcomes of picking an orbwhich made two of the participants curious.

The UFOship thatarrives on top of theclimberatthe end wasanotherelementofthe game that triggered curiosity for one of theparticipants.Hestated thatheexpected the enormous spaceshiptocomebackand pickhim up. Thearrival of theUFO left himwith questions in the end.Althoughthe gameends at that point, it still gives theplayers things to thinkabout even after thegame.

One of theparticipants reported that noneofthe aspectsinthe game awakened curiosity in him because he wastoo focused on climbing.

The pause created during thegame where theplayerhas to makeachoice to continue climbing gave all of theparticipants exceptone asense of progression. Giving players amilestonetoreachmakes them curious about what is to unfoldnextand creates expectations.Theseaspects prevent the game from becoming stale. The participants are further questioned about themotivation levelreaching amilestonegives to progress further. As seeninFigure 5.12, all participants exceptone feltrelativelymotivatedto

76 5.4. Results continuewith the game after theinteraction with theowl.

Figure 5.12: Motivation leveltocontinueclimbing after themilestone.

5.4.5 OverallResults of ApplyingGame Design Element The purpose of thedatacollected from theparticipantwas to ﬁndout howlikely it is to apply generally acceptedgame design practicesand methods to the virtual reality platform.The core game design elementsaesthetics, story,mechanics, and technology are all presentinAstroclimband they complement eachother. Although the use of these elementscan get transitioned to virtualrealityplatformssuccessfully,thereare other coreconcepts such as immersion,usabilityand game feel that need to be looked into because theymean diﬀerentlyfor VR games.

Immersion is themost importantaspect of virtual reality. Every other element used in agame should trytoadd to the overall immersion leveltoincreasethe satisfaction rateofplayers. The importance of immersion increases further if thephysical play area needs to be in harmonywith the world created in thevirtualrealityenvironment. In this case, the alignmentofthe physical wall, the climbing holds on them, the virtual glovesand shoes should matchpositioning-wiseasperfectly as possiblewith theirvirtual representations,otherwise playingthis game would notbepossible at all. Thisisdone by the calibration processes at thestart of theapplication and the(almost)perfect alignmentcarried on throughoutthe game. If other physical objectsare involved in the game design besides theVRequipment,furthermeasures have to be taken to keep the immersionatahighlevel.Besides the calibration process and providing acore concept of being abletoclimbinavirtualenvironment, in-game elementsshould make

77 5. Evaluation

players immersedinthe scenario.The data gathered from theclimbing sessions that are discussed in this section previously clearly states that theparticipantswere immersedin the game. Creatingthe environmentfor playersinvirtualrealityshould take“presence” into account.Presence alsocalled “telepresence” is aphenomenon that makes peoplebe abletobecomeconnected with aworld outside of their bodies with the helpoftechnology. Sinceplayers become physicallyapart of thegame they are playing,the experience with VR glassesproduces avisceralfeeling of being in asimulated environment. Creating this simulated environmentsuccessfully adds moretothe immersionlevelsofthe game.

Usability refers to maximizing the effectiveness and efficiency of thegame elements usedinagame while keepingthe players satisfied.Itisabout deliveringanenjoyable experience while keepingaway the unnecessary interruptionsorchallengesthat have not been designed by the developers [85]. As mentionedbefore, Astroclimbisbuilt upon Vreeclimber which makes theclimbing experience possiblebut alsobringslimitations with it.Asalready stated, the climbing experience became stale because of thepauses players hadtoencounter. Apossiblesolution to this issue would be providinghigher rotationspeed for thephysical wall. However, the game design couldalso find an in-game solutions which arediscussed in the next subsection. Thelow participation ratealsodid not help with testingthe game with peoplethat have no climbing experience at all. This lowdiversityofplayers prevented gatheringdataabout the challenge levelofAstroclimb for non-climbers. Ahigh rate challenge levelwouldalsoaffect usabilityinanegativeway. The overallgathered data, however, made itclear that unlike in non-VR digital game design,usability hasadditionalpit-holes if physical activity is involved in agame.

Gamefeelfor traditional video games is described as theintangible,tactile sensation experiencedwhen the playerinteractswith videogames [158]. Thisdeﬁnitionchanges forVRgames becausevirtualrealityenablesthe possibility of making theinteractions tangible. Astroclimbisaperfect example where it makessome of thecore elements such as thewall and theclimbing holds in the game tangible which enhances thegame feel and immersion directly.

Astroclimbtries to use adecent amountoftraditional game design elementsinitself such as story,game mechanics, replayability, challenge,and criticalthinking whilekeeping in mind that theVRand physical activityaspectsofitcan inﬂuence thesegame design elementsand require adaptations of these elements.

As thedatastatesall of thesegame design elementswere successfully applied with diﬀerentsatisfactory levels forthe players. The results also show thatthese applied game design elementsimprovedimmersion for theparticipants which enabled ahigherquality of user experience.Additionally,the absenceofmotion sickness helped withgiving this levelofquality experience.Therewere, however, some issuessuchasoccasional imperfect object alignments andlongpauses duringthe game which aﬀectedimmersion negatively.

78 5.5. Discussion

5.5Discussion

The evaluation showedthatvarious game design elementscan be applied to theVR platform,although some of them mayneed adjustments to makemore sense for the circumstances in thegame. Thelimitations and additional beneﬁts VR platformcan provide should be taken into accounttoenhancegameplay and increase playersatisfaction.

Experiencedclimbers were lessaware of theirenvironmentduring the climband noticed some of thecrucial objectsinthe environmentsuchasthe owlextremely late because of that. As stated in Section 2.3.1, climbers tend to focus on looking forward where the wall stands and do not paymuchattentiontotheir environments. To keep theclimbers’ focus on what is important, some of theobjects in the environmentcouldbere-allocated to drawmore attention from theplayers. Theused material for thevirtualclimbing wall, glass, can be usedfurtherfor this implementation.The owlcouldhaveappeared behind the wall and theinteraction could be designed diﬀerently.

One of theissues addressed by the fast climbers wasthe wait time thathad to experience because of therolling speed of theclimbing wall. An in-game design solution for that would be forcing the climbertotraverse horizontally with some diﬀerentdiﬃcultylevelsso thatthe rollingspeed would stopbeing an issuetocontinueclimbing.For that particular solution, astrict and challenging grippathcouldbemade visibletothe climberby changing thegripcolors. Moving horizontally wouldgiveenoughtime forthe physical wall to roll downwhichwouldeliminate the pauses.

Although theowl wasnot interpreted realistically,itisclearthat the lackofrealism does not have anynegativeeﬀectsonimmersion.This ideacan be supportedfurtherwhen the created virtual environmentisobserved. Ahanging climbing wall in the middle of the space,spaceships warping in andout,the audible sound eﬀectsinspace,wearing sports shoes,orchange of thenebulainthe blinkofaneye do not add anyrealism to thegame, however, the players accept this simulationasitisand the environmentmakes sense for them.

Combining physical activityand training with aVRgame creates anotherchallengefrom agame design perspective. Thegame lengthcan easily become an issueifthe physical activityistiring to an uncomfortable extent.Participants with less climbing experience stated thatthe game wastiring but it wasnot tiring enough to stopplaying it. The tiredness level of thegame is alsodirectly proportional to theplayer’s overallphysical training and condition at that pointintime whichdetermines theoutcome of thegaming experience.

Finally,itisalso interesting thatthe players with higher weekly gaming time had fewer problems with identifying the outcome of thechoices that were represented to them by the owl. It canalsobeexplained with other skills participants possess.The low participationmakes it diﬃcult to makeclaims about this observation,hence, further

79 5. Evaluation

studies should be conducted in this areatojudge theresultsfairly.

80 CHAPTER 6

Conclusion andFutureWork

As partofthis master’s thesis,aVR game called Astroclimbbased on theproject Vreeclimber wasdeveloped and aselection of various game design elementssuchas aesthetics,challenge,and replayabilitythatare usedfor video games were applied. Duringthe developmentprocess, the game went through modiﬁcationsand adaptations basedontesters’ feedback. In theend, aspace-themed game that focuses on climbing with aunique gameplay was developed.

The literatureresearchhas shown that thereare already similar approachestooverlay areal existingclimbing wall with virtualcontent.The applications builtuponthese approaches, however, are lacking content andfocus on onlyaligning the digitalscene with thereal world. Anotherlimitation of theseapproachesisthe limited climbable area whichisdictated by theheightofareal boulderwall. In comparison to these approaches, successful climbing-based VR games on themarket focusoncreatingVRexperiences with rich contentand ignore the realclimbing aspect sinceproviding players with areal climbable terrain or structure would be tooexpensive or non-proﬁtable. In Astroclimb, however, the rotationmechanism of the climbing wall enables endless climbing which createsopportunities to develop games withadvanced gameplaylogic.

Duringthe developmentstage of Astroclimb, various game design elementsare added to makethe game morecompelling to players while keepingthem immersedatall stages. The evaluation resultsshowedthat the players found the game aesthetically pleasing, the gameplayfun due to the application of aforementionedgame design elements. The use of theseaspectsinharmonyincreasedthe levelofimmersion in thegame and thequalityof userexperience.Ofcourse, thegame is not perfect and needsimprovementespecially in terms of gameplay for fast climbers so they do nothave to pauseclimbing because of reaching thetop of thephysical wall tooquickly.Furthermore,some objectscan be placedbetter in the virtualenvironmentinordertonot creatediscomfortfor theplayers.

81 6. Conclusion andFuture Work

The lengthofthe game is alsostill problematic although it wasshortened once already. The visibleexhaustionofplayers towards the end of thegame showsthe game’soverall diﬃculty duetoits physicalactivityaspect.

82 APPENDIX A

Step-by-step Test Procedure

1. Operators make surethatthe test person followedthe Covid-19procedure until they entered the workshop.

2. The testpersondisinfects his hands with the provided handsanitizer.

3. The test personreadsand ﬁlls out thedeclaration of consent, theinformation papers,and the pre-climb questionnaire.Ifthey have anyquestionsregardingany paper, they get answered.

4. VR headset and trackers get disinfected by one of theoperators.

5. The test personisasked about theirshoesize to provide them with aﬁtting pair of climbingshoes.

6. The testpersonwears the safetysuit.

7. Test personsits on achair and wears climbing shoes. At the same time,the person getsabrieﬁng about what to expect during theclimb. Further questions get answered if there are any.

8. The VIVE Trackers get attachedtoclimbing shoesbyone of theoperators.

9. The test persongets informed abouthow to wear theVIVE Trackers on theirhands, and they followthe instructions.

10. The test personwears the VR headset and stands away fromthe climbing wall at a certain point.

11. Safetyropes get attached to thecarabinersofthe safetysuit.

83 A. Step-by-step Test Procedure

12. The test persongets informedabout holding theirfeetand handswith palms parallel to the groundand ﬁngertips facingstraighttowardsthe climbing wall. (picture)

13. The application starts.

14. Hand and feet calibration commences. After this, thetestpersongets informed to move theirhandsand feet freelyagain.

15. Wall calibration commences.

16. Once the door of thehanger in thegame opens, thetestperson can start climbing whenever they want and/or keep observingtheir surroundings.

17. The test person plays the climbinggame which lasts approximately4minutes.

18. In theend,the test personcan get theirhands and feet oﬀ the grips.

19. The operator that is responsible for holding thesafety ropesofthe climberlowers the climberslowly to the ground.

20. The safety ropegets removedfrom the carabiners oncethe test person is on their feet.

21. The VR headset, VIVE Trackers get removed.

22. The testpersongetsfreedfromthe safety suit.

23. The testpersontakes oﬀ the climbing shoes.

24. Oncethe test person is ready,heisasked to ﬁllout the post-climbquestionnaire.

25. If thetest person hasadditionalremarkstowardstheir current experience ashort interviewisconducted.

84 ListofFigures

2.1 With the helpofthe controller the userisable to select alocationonthe small globeand ﬂy towardsit. [56]...... 8 2.2 An interviewer tries out one of theﬁrst prototypes of Oculus VR at E3. [42] 9 2.3 AvarietyofGoogle Cardboards. [54] ...... 9 2.4 Global VR headsetmarket share, by application, 2020 (%)[130] .....10 2.5 From left to right: HTC VIVE [178], SonyPlayStation Move [126], Oculus Touch[118], ValveIndex[70] controllers...... 13 2.6Anexample foragaze-basedselection cursor in Unity.[94] ...... 14 2.7The potentialofVRapplicationsbycategory.[60] ...... 15 2.8Traversing options in Half-Life: Alyx. [11] ...... 17 2.9The playerhas to slicecubes withthe correct ligtsaberofcolor.[62] ... 19 2.10 Players use theiravatar hands to interactwithvarious objects. [80] ....19 2.11 The Elemental Tetrad [143] ...... 21 2.12 Interactivecycle in the playexperiencebyFabricatore [37] ...... 24 2.13 Content-zonediagram for acomfortableuser experience [5]...... 27 2.14 Comfortable angles of neckrotation [5] ...... 28 2.15 Harness and climbing shoes forindoor climbing.[150] ...... 33 2.16 Ropesystemsetup for indoorclimbing. [9] ...... 33 2.17 What competition looks likeinThe Climb2.[25] ...... 34 2.18 The climber’s verticalmovementonthe wall is mostly restricted. [81] .. 34 2.19 VR equipment used forAstroclimb. [176] ...... 35 2.20 The stance theplayerhas to takefor calibrating handsand feet...... 37

4.1Across-section of thehangar -the startingpointofthe game...... 50 4.2The massivespaceship thatbringsthe playertothe climbingwall. .... 50 4.3The mechanical owldesignedfor Astroclimb...... 52 4.4The endofﬁrstsegmentinthe game...... 52 4.5 Time and heightindicators are placed on theleft avatarhand, whilethe score is on theright avatarhand...... 56 4.6 An early design stage of themechanical owlinBlender...... 58 4.7 The hoverboard designed for players to stand up on before the climb. .. 58 4.8 The moon scene...... 59 4.9 The asteroidbelt scene...... 59 4.10 From lefttoright: The destroyer, Viper,TIE ﬁghter...... 59

85 5.1 The Vreeclimber wall...... 66 5.2 Operator holding theclimber...... 67 5.3 Carabiners with the safety ropes...... 67 5.4 Extrasafetymeasureswith ropesand arobust bar...... 67 5.5 Trackerishiddenbetween thebodyand the wall...... 68 5.6 Trackerishiddenbetween thehand and thewall...... 68 5.7 Effectsofdifferent game design elementsonimmersion...... 71 5.8 Effectiveness of some of thein-game experiences...... 73 5.9 Effectsofthe chosen orb on thegame experience...... 73 5.10 Participants’ thoughts on orbs...... 75 5.11 Likeliness to playthe game again...... 76 5.12 Motivation leveltocontinueclimbing after themilestone...... 77

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