Design Guidelines for Multiplayer Video Games on Multi-touch Displays KHAIRI REDA, DENNIS CHAU, YASSER MOSTAFA, NAGARAJAN SUJATHA, JASON LEIGH, ARTHUR NISHIMOTO, EDWARD KAHLER, and JASON DEMETER, University of Illinois at Chicago, USA The proliferation of multi-touch, tabletop display systems during the last few years have made them an at- tractive option for interactive, multiuser applications such as museum exhibits and video games. While there is a large body of research on the use of multi-touch and tabletop devices in general purpose applications, far less research has investigated the use of these systems in video games and other entertainment applications. This paper provides a set of guidelines specific to multi-touch displays that can be used to augment existing video game development principles. Through example, we illustrate how the unique capabilities of multi- touch displays can be leveraged to create unique forms of gameplay that offer highly engaging multiplayer game experience. We describe three multiplayer games that have been developed by students as part of an interdisciplinary course in video game design. Categories and Subject Descriptors: K.8.0 [Personal Computing]: General—Games General Terms: Video Games, Multi-Touch, Multiplayer Additional Key Words and Phrases: Multiplayer video games, multi-touch displays ACM Reference Format: Khairi Reda, Dennis Chau, Yasser Mostafa, Nagarajan Sujatha, Jason Leigh, Arthur Nishimoto, Edward Kahler, and Jason Demeter. 2014. Design guidelines for multiplayer video games on multi-touch displays. ACM Comput. Entertain. 11, 1, Article 1 (March 2014), 17 pages. DOI: http://dx.doi.org/10.1145/2543698.2543699 1. INTRODUCTION Multi-touch displays are touch-sensitive screens that allow users to interact with graphical applications using their fingers. Unlike traditional touch-screens commonly used in ATM machines and other consumer devices, multi-touch displays are able to register a large number of distinct touch points (typically in the tens) simultane- ously. This allows users to interact with the display using more than one finger or hand at a time, which expands the possible interaction schemes and enhances user experience. Additionally, a multi-touch screen allows multiple users to simultaneously interact with the display when the screen surface is large enough to accommodate them. This enables possibilities for a new generation of collaborative, multi-user, interactive applications. The enhanced user experience has made multi-touch displays an attractive option for many applications in which multiple people need to collaborate to achieve a common goal. For example, museums are exploiting multi-touch displays to build interactive exhibits in which visitors work together to complete specific tasks supporting a common Author address: Khairi Reda (corresponding author), Department of Computer Science, University of Illinois at Chicago; email: [email protected]. Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies show this notice on the first page or initial screen of a display along with the full citation. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, to republish, to post on servers, to redistribute to lists, or to use any component of this work in other works requires prior specific permission and/or a fee. Permissions may be requested from Publications Dept., ACM, Inc., 2 Penn Plaza, Suite 701, New York, NY 10121-0701 USA, fax +1 (212) 869-0481, or [email protected]. c 2014 ACM 1544-3574/2014/03-ART1 $15.00 DOI: http://dx.doi.org/10.1145/2543698.2543699 ACM Computers in Entertainment, Vol. 11, No. 1, Article 1, Publication date: March 2014. 1:2 K. Reda et al. learning goal [Leigh 2009]. Scientists are also leveraging these displays to generate interactive visualizations that support collaborative investigation and analysis of com- plex, large datasets. More recently, video game developers have started to view multi- touch displays as an emerging platform for multiplayer games. Traditional computer games such as Pong [Gross et al. 2008] have been “ported” to tabletop multi-touch platforms, allowing a social, multiplayer experience. A number of characteristics make multi-touch displays an attractive platform for multiplayer games. In video game consoles and PC-based games, each player receives a separate view of the environment, and interact with the game using a dedicated con- troller which typically allow the player exclusive control over a subset of characters or objects in the game. By contrast, players in tabletop multi-touch displays share a single environment, and interact with the game using a shared but powerful interface that enables complex interactions to be conveyed intuitively. This allows for a more social, face-to-face interaction between the players. Moreover, because the players share the same input device, they do need to have exclusive control over certain characters or objects, enabling a more fluid control scheme to be used in the game. The improved social interaction, and the ability to cooperatively share control over the game enables unique interaction modalities that encourage collaboration between players and foster high-level problem solving, leading to increased enjoyment by players. These character- istics can also be exploited by serious video games to offer engaging, social gameplay in which participants collaborate to play the game while learning the intended concepts at the same time. While there are well-established design paradigms and principles for games target- ing traditional video game hardware (such as consoles and PCs), these techniques fall short when applied directly to radically different hardware platforms such as multi- touch displays. As the hardware interface changes, the interaction scheme associated with the game can change dramatically, which in turn can significantly influence many aspects of gameplay. For example, a multiplayer game for a tabletop multi-touch display has to present a consistent view for all participants regardless of the position they are viewing it from. Game designers need to be aware of these aspects in order to leverage the affordances of multi-touch displays and design around their limitations. There have been some attempts at porting existing video games to multi-touch platforms (For ex- ample, Warcraft [PQ-Labs 2008] and The Sims [Tse et al. 2007]). However, these ports often resort to emulating the mouse with input from the multi-touch screen, resulting in a single-player game that does not take advantage of the multiplayer capability of multi-touch displays. The goal of this paper is to aid game developers in understanding how the unique capabilities of multi-touch displays can be leveraged to create unique forms of gameplay that offer highly engaging multiplayer gaming experience. Additionally, the limitations of the technology and their effect on gameplay are also illuminated. We discuss these issues in the context of a number of games that were developed during two iterations of a semester-long video game design course. During this course, groups of students majoring in Art and Computer Science designed and developed, from the ground-up, video games for TacTile, an LCD-based multi-touch display that supports as many as 500 simultaneous touches [TacTile 2008, Leigh et al. 2009]. It is important to note that we define multi-touch displays in this paper as displays that can sense more than twp simultaneous touches, and can physically accommodate at least two users. Therefore we do not include iPhone and Android games as part of this discussion. The rest of the paper is organized as follows. Section 2 reviews previous research on multi-touch video games. In Section 3, we discuss the methodology used in the research leading to the conclusions of this paper. Section 4 describes the development platform. Section 5 describes three different multiplayer video games designed for TacTile, and ACM Computers in Entertainment, Vol. 11, No. 1, Article 1, Publication date: March 2014. Design Guidelines for Multiplayer Video Games on Multi-touch Displays 1:3 documents different approaches for effective multiplayer gameplay. Section 6 summa- rizes the lessons learned and provides some guidelines for prospective developers of multi-touch video games. We conclude the paper in Section 7 and give future research directions. 2. RELATED WORK Tabletop and multi-touch displays have attracted large interest from the Human- Computer Interaction community due to their intuitiveness and suitability for group- oriented tasks. There is a large body of research on the use of these displays in collabo- rative, computer-supported tasks. A classical example is the work of Scott et al. [2003]. The vast majority of the literature on multi-touch and tabletop displays however fo- cuses on general-purpose, work-oriented tasks, as opposed to video games. While many of the conclusions and guidelines found in that body of research can be conceivably generalized to games, there are a number of unique factors that have to be consid- ered when designing multiplayer video games, including enjoyment and competition between players. In recent years, the interest in the application of multi-touch and tabletop displays to multiplayer gaming has increased. A number of classical video games have been ported to these platforms. One example is a multi-touch adaptation of the famous Atari Pong game [Gross et al. 2008]. The game is played with a single gesture that consists of a two-finger tap to form a racket and bounce the ball. Esenther et al. describe two multiplayer, multi-touch games [2005]. In the first game, players compete to find a special ball with a swirling pattern out of groups of blue balls. The hardware platform allows the identity of the player touching the table to be reliably deduced. Therefore, the game knows the identity of the winning player who finds the special ball first.