Rethinking Real-time Strategy Games for Virtual Reality Samuel Truman, Nicolas Rapp, Daniel Roth, Sebastian von Mammen University of Würzburg Würzburg, Germany {samuel.truman,nicolas.rapp}@stud-mail.uni-wuerzburg.de,{daniel.roth,sebastian.von.mammen}@uni-wuerzburg.de ABSTRACT and extended, quickly reaching the point where previously distinct Recent improvements in virtual reality (VR) technology promise the genres such as creative sandbox “god games” like Black & White opportunity to redesign established game genres, such as real-time or Townsmen merge with RTS mechanics. While close adherence strategy (RTS) games. In this work we have a look at a taxonomy to current genre definitions is not mandatory [3], we understand of RTS games and apply it to RTS titles for VR. Hereby, we identify that VR can support the core mechanics of RTS games to yield possible difficulties such as the need for novel means of naviga- even more intense, diverse, joyful game experiences. To support tion in VR. We discuss conceivable solutions and illustrate them this notion, this paper discusses the realization of common RTS by referring to relevant work by others and by means of AStar0ID, game principles in VR. As part of this discussion, we propose a an exploratory prototype VR RTS science fiction game. Our main continuum of perspectives which illustrates the differences among contribution is the systematic inspection and discussion of foun- RTS games in terms of visualization and input modalities. We iden- dational RTS aspects in the context of VR and, thus, to provide a tify design challenges for VR RTS games, e.g. in terms of scaling substantial basis to further rethink and evolve the RTS genre in this or cyber sickness, and suggest possible solutions. Additionally, we new light. highlight some newer and enhanced game mechanics, which arise from the migration of RTS to VR. CCS CONCEPTS To provide a foundation for this discussion, we systematically introduce RTS games, their evolution, their elements of play, and • Human-centered computing → Interaction paradigms; Visual- their genre definition in Section 2. In Section 3, we first present ization theory, concepts and paradigms; Interaction devices; a prototype VR RTS game and next, we consider the taxonomic ACM Reference Format: dimensions of RTS games in general in the context of VR. We Samuel Truman, Nicolas Rapp, Daniel Roth, Sebastian von Mammen. 2018. summarize our work in Section 4 and have a brief outlook on Rethinking Real-time Strategy Games for Virtual Reality. In Foundations of potential future works in this direction. Digital Games 2018 (FDG18), August 7–10, 2018, Malmö, Sweden. ACM, New York, NY, USA, 6 pages. https://doi.org/10.1145/3235765.3235801 2 RELATED WORK 1 INTRODUCTION In this section, we first briefly put VR RTS games in the historical VR recently hit the consumer market, providing new opportunities context of the RTS genre, emphasizing the evolution of play. After for video games. VR is currently broadly understood as the presen- a subsequent summary of the basic elements of play of RTS games, tation of a 3D virtual environment by means of a head-mounted we conclude this section with an analysis of the RTS genre in the stereoscopic display that is coupled to the physical head movement context of an established, multi-dimensional taxonomy. of the user. In addition, VR empowers the user to seamlessly in- teract with the virtual environment, for instance by means of 3D 2.1 A Brief History of RTS Game Mechanics controllers. VR technology increases immersion by overcoming The term RTS emerged from a collection of gaming habits and sensory inconsistencies between reality and digital worlds, e.g. by game mechanics [4]. RTS games combine the concepts of wargames tracking the players’ movements, by minimizing latency, and by and real-time control, of strategy and action games [5]. Their typ- increasing pixel or color resolution [9]. As a result, VR allows the ical game mechanics evolved over time. In this context, several player to become fully present in a virtual world and fosters the games particularly influenced the genre. For example, Modem Wars sense of “being there” [10]. In the context of RTS, VR can increase (1988) lacks features such as resource management but introduced the immersion into realistic strategic command scenarios but also combat related concepts adapted by later releases such as a mul- bring about novel futuristic elements of play by deploying differ- tiplayer mode and fog of war1 [4]. The basic dynamics of Dune ent perspectives, augmented views and interaction opportunities. II—harvesting resources, building bases, producing units and fight- As a result, RTS game mechanics can be redesigned, intensified ing battles to achieve victory—were inherited by subsequent games Permission to make digital or hard copies of all or part of this work for personal or as well. Warcraft: Orcs & Humans (1994) extends Dune II’s core classroom use is granted without fee provided that copies are not made or distributed feature by a multiplayer mode [4]. Simple controls, e.g. to select for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than ACM a unit or building by pointing and clicking as well as selection of must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, multiple units render Command & Conquer quite accessible. These to post on servers or to redistribute to lists, requires prior specific permission and/or a features can be found in almost every modern-day RTS game. Over fee. Request permissions from [email protected]. FDG18, August 7–10, 2018, Malmö, Sweden © 2018 Association for Computing Machinery. ACM ISBN 978-1-4503-6571-0/18/08...$15.00 1Fog of war hides unexplored areas while revealing areas the player’s units have https://doi.org/10.1145/3235765.3235801 already traveled about. FDG18, August 7–10, 2018, Malmö, Sweden time, camera perspectives have fundamentally changed. Originat- and low level commands which is reflected in the selection of the ing from an exclusively two dimensional top-down perspective, offered views. This balance is also reflected in common choices most modern RTS games utilize 3D models to allow for a multitude of input modalities. Selections and multi-selections in overview of camera perspectives [1]. The shift to free camera perspectives perspectives can be performed well using a mouse [8], whereas made the transition to VR possible. adjusting configuration details is supported by the breadth and precision of keyboard inputs. 2.2 RTS Basic Elements of Play In RTS games, the players need to manage interacting, interde- 2.3 Taxonomy pendent units in real-time, pursuing some overarching strategy Based on the outlined goals, mechanics and common features of that culminates in shorter term tactics [11]. In this context, self- RTS games, we shed light on RTS based on an established multi- organization plays an important role, i.e. the extent to which the dimensional taxonomy [1] that sets them apart from other game units coordinate their local behaviors by themselves and thereby genres. The first dimension for the classification of the genre is succeed in achieving globally defined goals [12]. the environment of the game. The environment in RTS games is Often, RTS games reflect military conflicts, whereby an oppo- mostly dynamic which means that elements of the map can change nent’s defeat is established once one’s army, economy or base is over the course of the game. In addition to buildings being built destroyed. Certain RTS games can be won by aggregating achieve- or torn down and units moving, trees might be chopped down or ments as in The Settlers 7. Economic success is important to build, planted (The Settlers IV) and landscapes remodeled (Maelstrom: maintain, and repair one’s gaming assets—including buildings, mili- The Battle for Earth Begins). There are, however, also titles like tary units, or advantageous technologies. These reinforce economic Warhammer 40.000: Dawn of War with static environments that growth by mining, refining, harvesting or raiding. The specificity cannot be manipulated. Next to the environment of a game, its pace of the resources yields complex networks of interdependencies that determines its genre. As strategic thinking and tactical deployment need to be mastered by the player [11]. All the elements of play occur concurrently, the final pace of an RTS title depends onthe mentioned so far can be transfered to VR without the need for number of decisions needed/possible per time. This heavily depends crucial changes. on the actual time various processes take in the game. The taxo- Typically, gameplay takes place in limited areas called maps [11]. nomic dimension of time is arbitrary in RTS games, i.e. building a Over time, map design and presentation evolved from planar 2D house in the game, for example, does not require the same time as textures to 3D terrains with differences in height. Maps of Dune II, building a house in the real world. As a result, there are considerable for example, are two-dimensional and show no elevations of the differences regarding pace and time between RTS titles—often the terrain but drawn mountains and valleys. Later games relied on player can even adjust the speed himself. The continuous, arbitrarily three-dimensionally rendered maps, indicating heights by means mapped real-time in RTS is accompanied by a geometrical, con- of perspective top-down or isometric views. Common elements tinuous topography that defines basic relationships between the of modern map design are hilly terrains, uncrossable territory for involved units. Due to the clear definitions of winning or losing (Sec- ground units such as mountains, obstacles or abysses and in some tion 2.2), RTS games are considered finite in terms of their goals, or cases conditionally traversable territory such as rivers or seas (see teleology.