Touchscreens vs. Traditional Controllers in Handheld Gaming Loutfouz Zaman Daniel Natapov Robert J. Teather Department of Computer Science and Engineering York University, Toronto, Canada {zaman, dnatapov, rteather}@cse.yorku.ca ABSTRACT more compact form-factors [4]. Consequently, one can find a We present a study which compares touchscreen-based controls variety of such devices on the market today. Additionally, the and physical controls for game input using Ubisoft’s recently released Apple iPad has the potential to popularize Assassin’s Creed: Altair’s Chronicles. Our study used the Apple touchscreen-based handheld computing in the large screen mobile iPhone as a representative touchscreen-based controller and the domain. Nintendo DS for its physical control pad. Participants completed a Gaming is arguably a primary use of these devices. Currently, game level four times on each platform. Level completion time there are far more games available for touchscreen handheld and number of player deaths were recorded. Results indicate that devices such as Apple’s iPhone than for leading game-dedicated physical buttons allowed significantly better performance than handhelds. In September 2009, during Apple’s “It’s rock and roll” virtual buttons. Specifically, the number of character deaths on event, the company announced that there are 21,178 game and the iPhone was 150% higher than on the DS, while level entertainment applications available in the Appstore, as compared completion time on the DS was 42% faster. The learning curve for to 607 Sony PSP games and 3,680 Nintendo DS games [23]. As the touchscreen version of the game was also steeper. Participants of February 2010, there are 4,118 game titles in the Android strongly preferred the physical buttons of the Nintendo DS. We Market [1] and 254 game titles in Windows Marketplace for conclude that either game designers should consider alternative Mobile [18]. Additionally, the State of Game Development input methods for touchscreen devices, or hardware designers Survey revealed a recent surge of iPhone developers [11]. should consider the inclusion of physical controls. According to the survey, mobile developer support increased to 25% of game developers in 2009-2010, from 12% in 2008-2009. Categories and Subject Descriptors Nearly three quarters of these developers are targeting iPhone and H5.2. [User Interfaces]: Haptic I/O, Input devices and strategies iPod Touch development - more than twice the reported support (e.g., mouse, touchscreen), User-centered design for dedicated game platforms such as the Nintendo DS and Sony PSP. General Terms Games for handheld devices often use the touchscreen and Design, Experimentation, Human Factors. accelerometers for input. Game developers strive to utilize these Keywords input methods when developing games for these platforms. However, certain gameplay styles, such as “hack and slash”, Tactile feedback, mobile device, touchscreen, mobile interaction, classic platformers, and first-person shooters are difficult to fingertip interaction, handheld gaming, haptic feedback, game design without the use of physical-based controls. Consequently, input. Appstore games such as Assassin’s Creed: Altair’s Chronicles, Resident Evil 4, Ghosts ‘n Goblins, CastleGuard, N.O.V.A: Near 1. INTRODUCTION Recently, there has been a departure from mobile devices using Orbit Vanguard Alliance, Grand Theft Auto: Chinatown Wars, physical keypads and buttons towards devices exclusively using etc. afford indirect input via virtual touchscreen-based controls. touchscreens [4]. This trend has been popularized by Apple’s These games are designed with a standard physical controller in iPhone (see http://www.apple.com/iphone/). The versatile mind. Consequently, they display virtual controls on-screen, touchscreen minimizes the need for other physical input which the player interacts with via the touchscreen. mechanisms while maximizing the display size relative to the Popular opinion in the gaming community suggests that these device [8]. This allows for efficient pointing and touch-based touch-based directional pad controller “simulators” afford input. By eliminating the need for keypads these devices allow for performance inferior to that of traditional physical button controllers. In this paper we investigate the validity of this claim using the game Assassin’s Creed: Altair’s Chronicles. We hypothesize that physical controls will indeed outperform touch- based controls, due to the haptic feedback they provide. We also provide an overview of related work, addressing the limitations of hand-held touchscreen gaming. Mobile device manufacturers and game developers should use this work as a guideline, when developing games for these platforms. accurate interactions in an eyes-free setting than systems that 1.1 Related Work offer no tactile feedback, or those that use a single vibration 1.1.1 Touchscreens motor [28]. Touchscreens allow a great deal of flexibility, but there are a number of tradeoffs. Small touchscreens are impractical because Pitts et al. [21] demonstrated that multi-modal feedback is the selection point is ambiguous due to the size and softness of preferred over visual feedback alone in a study involving driving the user’s fingertip. This makes selection of small targets difficult simulation while using a handheld device. Combining visual, and error-prone [4]. Even when screen sizes are large enough so audible and haptic feedback was consistently rated highest. These to display larger targets (e.g., iPhone), finger-based interaction results indicate the importance of haptic feedback in systems occludes parts of the display, covering up valuable pixels and where user attention is divided and visual contact with the making it harder to see the results of interaction [8]. Multi-touch interface is limited. We suggest that these findings extend to displays exacerbate these problems [8]. Occlusion is reduced by hand-held gaming; the player’s attention is focused on playing the stylus use, but this can be cumbersome as it requires the use of an game, and the touchscreen control buttons are occluded by the additional object [8]. thumbs. These issues may be addressed by back-of-device interaction – Some device manufacturers attempt to address the lack of tactile adding a touchscreen (or touch surface) on the back of the device, feedback. The Blackberry Storm [5], for instance, features to avoid finger occlusion [4][13][22][25][26][27]. However, this SurePress technology in addition to the capacitive touch kind of interaction has yet to be commercially deployed and technology [3]. The manufacturer of SurePress claims that this accepted by the consumers. It is also unclear how it can be provides better typing accuracy due to the addition of tactile adopted for handheld gaming. feedback. With SurePress, the screen is essentially one physical button that the user can press down for a "click" action. The idea The Shift technique [24] redraws occluded pixels next to the was first established by Mackenzie and Oniszczak [17], when fingertip. This is likely more useful in text-entry on soft they introduced a tactile touchpad. In their study, an actuator was keyboards, and may not be practical when simulating traditional placed beneath the touchpad. This allowed clicking and dragging game controllers on a touch-screen for hand-held gaming. on the surface in a more natural way than using an external button SideSight [8] mitigates the need for user input on the screen, or in or doing a lift-and-tap operation (a series of three taps to activate fact on any part of the device itself. It instead uses proximity click-and-drag mode). The authors’ study found that the tactile sensors to divert the user input region to the areas on either side of condition was 20% faster than lift-and-tap and 46% faster than the device. While this solves the problem of occlusion on smaller using a button for selection. screens it may be impractical for hand-held gaming as it requires the user to lay the device on a surface while using it. 1.1.3 Game Design Understanding controller and input issues is critical to game 1.1.2 Tactile Feedback design, as the player interacts with the game by way of the inputs Tactile feedback is one possible solution to overcome gaming used. Yet, relatively little work has been done in this area. None issues on touchscreen mobile devices. We consider research that of the above studies directly address issues in touchscreen hand- compares keyboard text entry on mobile devices here. Hoggan et held gaming, such as occlusion, lack of tactile feedback and small al. [14] demonstrated that physical keyboards and tactile screen size. It is possible to create new input paradigms for touchscreens had significantly fewer typing errors than standard touchscreen devices. For example, one can use the accelerometer touchscreens. The authors suggest that better tactile actuators as input, and tilt the device to simulate turning a car steering could improve performance of tactile touchscreens even further. wheel. If “traditional” (i.e., button-based) control methods are The authors also suggest that device manufacturers should use used, there are two alternatives: either develop games for devices tactile feedback in their touchscreen devices to regain some of the with physical buttons, or emulate such controls on touchscreen feeling lost when interacting on a touchscreen with a finger. devices. The latter is the current strategy adopted by game developers, who rarely have control