Location Aware in Mobile Gaming

Transcription

1 Location-based gaming Be aware, everywhere! Wouter Wiegmans Bachelor Thesis Telematics, University of Twente, Enschede, The Netherlands Supervisors: Dr. ir. Johan Koolwaaij (Telematica Instituut) Ir. Martin Wibbels (Telematica Instituut) Dr. ir. Aart van Halteren (Universiteit Twente) Enschede, The Netherlands January, 2005

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3 Abstract Context-awareness is the ability of computing devices or applications to detect and sense, interpret and respond to aspects of a user's local environment and the computing devices themselves. When the concept of context-awareness is applied to mobile gaming, the real and virtual world can dissolve in each other, and the gaming application can become aware of the physical location of the player to which it can respond. Context-awareness adds a completely new dimension to mobile gaming; enhancing the overall mobile gaming experience. Therefore, context-aware services provide a great opportunity for improving existing, and developing new mobile games. This thesis presents the results of the actual development of a location-based game, preceded by and funded on an intensive literature study in the area of location-based gaming

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5 Table of contents 1. Introduction Motivation Objectives Approach Structure Context Awareness in mobile gaming What is context Context Awareness Contextual information: Location Sensing the context: Location Mobile gaming WASP & Mobile Life WASP MobiLife Current work Introduction Location-based Games Comparison Location-based platforms Game Concept Requirements The Game Concept Playing the Game Locality Groups The competition Future work The Game Architecture Other Game Architectures The Pop Star Game Architecture Implementation Building a game world on the real world Building the actual game Database structure The game running Evaluation Requirements Functionality Conclusion Conclusions & Future work Conclusions Future work References

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7 Preface One could say that this thesis presents the results of my bachelor assignment on location-based gaming. Although this is true, as you will find out while reading it, I would say not all the results are included in this thesis. Of course, all the technical details are covered, but only few is written about the personal results of this assignment. In my opinion, being a student means the personal results of an assignment are as important as the technical results. I would like to thank the Telematica Instituut for giving me the opportunity to do my bachelor assignment at the Telematica Instituut and thereby allowing me to learn, not only within the area of my study Telematics, but also about myself as a person, and about the daily life within a research-focused environment as the Telematica Instituut. I would especially like to thank my supervisors; Johan Koolwaaij, Martin Wibbels and Aart van Halteren for their support during the assignment. I enjoyed our (two)weekly meetings and appreciated your remarks and suggestions. Moreover, I would like to thank all the employees at the Telematica Instituut for contributing to an open, friendly and cooperative working environment. Looking back, I am certain that doing my bachelor assignment at the Telematica Instituut was the right decision. I hope you will feel the same. Enschede, 22 nd of January Wouter Wiegmans - 7 -

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9 1. Introduction Context awareness is the ability of computing devices or applications to detect and sense, interpret and respond to aspects of a user's local environment and the computing devices themselves. When this concept is applied to mobile gaming, aspects of the user s environment can be brought into the game; the gaming application becomes aware of the physical location of the player to which it can respond. When alliances between players can be formed, players will have access to different levels of context information, e.g. opponents can only see the user s location when they are within range, whereas allies have access to his location from anywhere and also to his status, mood, tactics et cetera. This chapter presents an introduction into the assignment on location-based gaming, which led to this thesis. The motivation, objectives, research questions and approach are discussed below Motivation A lot of research on context-aware services is available and currently in progress. Every so often, research should be translated in practice. Moreover applying technologies in practice often provides new insights for future research. The Univerisity of Twente and the Telematica Instituut are both active in the research on contextaware services. Using the results of the WASP project, lining up to both the European MobiLife project and the Freeband Awareness project (which continues with the WASP results), this assignment has performed the function of applying research into practice and providing new, interesting insights for future research Objectives The focus of the assignment will be on context providing (location), context exchange and group aspects in a mobile gaming setting. The goal is to design a mobile gaming application that uses the player s physical location and alliances to enhance the gaming experience. The application will use appropriate generic components from the WASP platform whenever possible Approach A straightforward approach is taken in this assignment. The actual implementation of the locationbased game is preceded by a literature study on location-based gaming and the design and development of a game concept. In general the approach is as follows: 1. Literature study (2 weeks) 2. Design of the gaming concept and functionality (2 weeks) 3. Choice of appropriate devices, location providers, et cetera (1 week) 4. Choice and set-up of a development environment for mobile applications (1 week) 5. Build a demonstrator version to be tested by the target group (2,5 months) 6. Report and presentation (2 weeks) 1.4. Structure The remainder of this thesis is structured as follows: Literature Study Chapter 2 presents the concept of context-awareness and applies it to mobile gaming. Chapter 3 presents related Telematica Ínstituut and University of Twente projects. Chapter 4 discusses location-based games currently (or in the past) available. Gaming Concept Development Chapter 5 presents the concept of the location-based game developed for this assignment. Chapter 6 proposes an architecture for the implementation of the gaming concept

10 Implementation & Evaluation Chapter 7 discusses the implementation of the gaming concept. Chapter 8 evaluates the prototype against the concept. Conclusions & Future work Chapter 9 presents the conclusions and future work possibilities based on the thesis

11 2. Context Awareness in mobile gaming This chapter presents the basic concepts of Context Awareness in mobile gaming. Before context-awareness can be applied to mobile gaming, a clear and shared understanding of the different concepts has to be established. This chapter consists of three parts. The first four paragraphs present the concepts context and context-awareness. Section 2.5 presents the Mobile Gaming concept. In section 2.6 the different concepts are combined into the key concept in this report: Location-based gaming What is context Although a lot of research is done in the area of context-aware computing, there is very little consensus on the exact definition of context. Several different definitions have been put forward in literature. In this report a generic definition of the term context, developed by Dey and Abowd [1], will be used: Context is any information that can be used to characterize the situation of an entity. An entity is a person, place, or object that is considered relevant to the interaction between a user and an application, including the user and application themselves. This definition of context is the general definition of context that was used in context(-aware) research by the Telematica Instituut. It was used in the development of the WASP services platform [2] and is present in the state-of-the-art of context-aware services [3] Context Awareness Context-aware computing deals with the ability of computer systems to be aware of the context to deliver improved services. This differs from traditional computer systems. These systems ignore contextual information. Their output is based only on the explicit input to the application (see Figure 2.1: Traditional applications, extracted from [3]). Figure 2.1: Traditional applications Context-aware computer systems not only base their output on explicit input, but also make use of knowledge of context (implicit input), gathered from the applications environment. This is represented graphically in Figure 2.2: Context-aware applications, extracted from [4]

12 Figure 2.2: Context-aware applications Context-aware computing can be divided into two categories: using context and adapting to context [3]. An example of the first category is an application that displays the distance of the car of the user to other objects. This function can for example be added to the board computer of a car. It does not adapt to the context, but uses the context to deliver relevant information to the user (for example when the user is parking or taking over another car on the highway) and thereby enhances the service delivered to the user of the board computer. An example of the second category is an application that beeps when the distance of the car of the user to other objects becomes too small. Based on contextual knowledge the computer system informs the user when his car is bound to collide with other objects given the current speed. The service adapts itself to the context. Both categories have to be covered by one definition, as both categories are aware of their context. Therefore a general definition of Dey and Abowd [1] is used: A system is context-aware if it uses context to provide relevant information and/or services to the user, where relevancy depends on the user s task. This definition is also used within the Telematica Instituut. It was for example used in the development of the WASP services platform [2] and was presented in the state-of-the-art of Context-aware services [3] Contextual information: Location Although different definitions of context and context-awareness exist, there are some simple forms of contextual information that designers do agree upon [1]. One of them, location, is relevant in this research. Location is the contextual factor that is currently used most in context-aware applications [3]. A key aspect in such context-aware applications is how the location information relates to the actions performed by these applications. For example, if someone is in New York, he is not interested in the weather forecast for Amsterdam and if someone is at work, he does not want to be disturbed by phone calls from friends, but as soon as he leaves work, he wants to be informed who called

13 Adding location information (implicit input) to an application creates a new class of services. Not only, it offers opportunities to improve current applications, it also allows new applications to be developed. However, to improve current or develop new applications, one should look into the complexity of adding location information to applications. Different location formats and different types of location determination exist, all with their own strengths and weaknesses [3] Sensing the context: Location Different formats for representing location exist [3]:? Global: using latitude and longitude? Referenced: using a point of reference (for example a central building)? Named: using the name of a location (for example a street name) One of the challenges lies in the interrelation between these formats. For example, if a user wants to know where he is, he does not want to know the latitude & longitude pair of his location (derived from his GPS handset), but he wants to know the name of the street he is in. The global format (latitude & longitude) should be converted to a named format (the street name). Different types of location determination exist. Only positioning techniques that are widely available, for example using cell phones and GPS, are discussed. Positioning techniques are based on determining the position of a mobile device of the user. These techniques rely on positioning technology in the mobile network, positioning technology in the handset or on a combination of both. Each technology has its characteristics including complexity, costs of implementation and accuracy of determination [3]. The most basic positioning technique in a mobile phone network is to use the current cell of the user. It relies mainly on the technology of the network. A network is able to identify the cell surrounding a base station in which the user is located. This technique can be further improved using timing or angle-of-signal techniques. Still, the accuracy is rather low, at most, in an optimal environment about 200m [3][12][13]. The second positioning technique in a mobile phone network is based on both the technology in the handset and technology in the network. E-OTD (Enhanced Observed Time Difference) is a technique that calculates the position of a mobile device using signals from three base stations. A LMU (Location Management Unit) should be available in the device to determine the location [3][12]. The third technique relies mainly on the technology in the handset. Assisted GPS (Global Positioning System) uses the signals from satellites together with the mobile phone network to determine the location. The exclusive use of GPS is possible too, although this requires better signals from positioning satellites and takes more time to position. The accuracy of these methods is about 5-30m [3][13]. Assisted GPS requires major investments from both the network operator and the user. The three positioning techniques described are the most common ones in mobile networks. It was not the intention to give a complete overview of positioning techniques. Using a mobile network is not the only way for positioning users. Another class of positioning techniques is based on wireless LAN (or short range radio in general). Instead of looking at mobile network base stations and cell phones, this class of techniques uses wireless LAN access points and mobile devices with wireless LAN access (for example a laptop or PDA). As this class (and other classes) requires a network of access points that is not as widely available as the mobile phone network it is not discussed in this report

14 2.5. Mobile gaming In this report the following definition for mobile gaming will be used: Playing computer games on a mobile device The prospects for mobile gaming are good. Although some differences exist in the expected growth in revenues (and in the definition of mobile gaming used), all analysts notice the emerging mobile gaming market. A recent (October 2004) report by media research consultancy Screen Digest predicts that the global mobile gaming download market will be a big industry by the end of 2004 ( 880m) increasing to 5,25 billion in 2010 [5]. The Wireless Communications Winning and Losing in Mobile Games predicts worldwide revenues from mobile games of nearly 2 billion dollars in 2006 [7]. And according to a Yankee Group analysis the market for mobile gaming will be worth $1.2 billion by the year 2006 for US operators [6]. These prospects all predict a considerable growth of the mobile gaming industry. These predictions were based on different research results or initiatives. Motorola predicts for example that by 2005, wireless services will hold 32% of the entertainment market (from 8% in 2000) [8]. Furthermore, in 2001, Motorola, (former) Ericcson, Nokia and Siemens joined forces and combined their resources and knowledge on mobile gaming in the Mobile Games Interoperability Forum [9]. This forum, together with nearly 200 companies, joint forces in the Open Mobile Alliance [10]. The MGI Forum intended to create specifications to allow producers to produce and deploy mobile games over multiple platforms [9]. The OMA also pursues interoperability, but does not focus on only games. Finally, a survey by Nokia indicated that nearly 50% of the people asked like to play games when waiting [11] Location-based gaming is the adding of the location aspect of context-awareness to mobile gaming. To sum up the relevant definitions of context, context-awarenes and mobile gaming: Context is any information that can be used to characterize the situation of an entity. An entity is a person, place, or object that is considered relevant to the interaction between a user and an application, including the user and application themselves. A system is context-aware if it uses context to provide relevant information and/or services to the user, where relevancy depends on the user s task. Mobile Gaming is playing computer games on a mobile device The following definition for Location-based gaming will be used in this report: Using the location of the mobile device as an aspect in mobile gaming to enhance the mobile gaming experience. This definition allows different kinds of location-based games. To be able to categorize the location-based games presented in chapter 4, the different kinds of games are addressed here. Some location-based games are ubiquitous games. Ubiquitous games are games that are situated and played in a real environment of which the game play is augmented by computational services to enhance and leverage the overall gaming experience [14]. Not all location-based games are ubiquitous. Location-based gaming is therefore not the same as ubiquitous gaming. Key in location-based gaming is the use of the location of the user as an aspect in the game. Key in ubiquitous gaming is taking functionalities of ubiquitous computing and applying them to computer games [9]

15 Some location-based games are pervasive games. Pervasive games are games that surround the player, 24 hours a day, everywhere he goes [43]. Not all location-based games are pervasive as some require fixed game arenas and fixed playing hours. Some location-based games provide an augmented reality: a combination of both real world and virtual reality components, but again not all location-based games do. Finally a division between games can be made on some technical aspects like the positioning technique used and the game arena (is the game available in a relatively small, pre-defined game arena, or in a complete city or even on a complete mobile network). For examples of location-based games see chapter

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17 3. WASP & Mobile Life The assignment presented in this report is related to two research projects of the Telematica Instituut; WASP and MobiLife. The WASP (Web Architectures for Services Platforms) project proposed a web services based framework to facilitate and speed-up the development of context-aware integrated mobile speech and data applications [16]. The WASP project is completed (duration August 2002 April 2004). This project is described in section 3.1. The strategic goal of the MobiLife Project is to bring advances in mobile applications and services within the reach of users in their everyday life by innovating and deploying new applications and services based on the evolving capabilities of 3G systems and beyond [17]. The MobiLife project recently was launched (duration September 2004 December 2006) [18]. This project is described in section WASP The WASP project is cooperation between the Telematica Instituut, the University of Twente and Ericsson. It was completed in April 2004 and the results included the WASP services platform. In this assignment a location-based game will be developed. The WASP services platform could prove useful in building this context-aware mobile application. This project can verify the claim that the WASP services platform facilitates and speeds up the development of context-aware applications. Section introduces the WASP services platform. Section describes the architecture of the WASP services platform. Section presents an example of an applying WASP in real life. Section 3.1.4, finally, addresses the link between WASP and this research The WASP services platform The goal of the WASP project was to create a supporting platform for mobile context-aware applications [19]. This platform (or framework) had to be based on web services. A web service is a software application, whose interfaces are defined, described and discovered using XML based standards and that supports direct interactions with other software applications using XML based messages via internet-based protocols [21]. The WASP services platform was developed with the assumption in mind that the creation of usable and feasible mobile applications will largely depend on the availability of flexible service frameworks, in particular when context-awareness application are to be developed [20]. Foundation for this assumption can be found in literature, in The Anatomy of Context-Aware Application Harter states that a services framework is required to deliver value-added services on top of existing low-granular services and knowledge sources [22]. To speed up the service creation process the services framework had to support the whole service lifecycle including definition, implementation and deployment [20]. In the WASP services platform, different modular services are provided to developers. Some of those services offer functionality, other (context) information and knowledge. All to speed up of the creation of mobile applications. The WASP services platform also provides an easy way for providers of services to offer and manage their services. Users of services are provided with an easy way for searching, finding and purchasing services. Finally, the use of web services enables services to utilize the intelligence of the mobile network. The WASP services framework is developed to be transparent, dynamic and platformindependent and is highly tailored towards convenience for developers [20]. Moreover, the WASP

18 services framework also offers an application platform that dynamically connects the users with information and services that are relevant to him The WASP architecture The overall architecture of the WASP platform is shown in figure 3.1, extracted from [23]. Figure 3.1 Overall overview of WASP architecture In this architecture four main groups can be distinguished: Service requestors, Service providers, Context providers and the WASP platform. These four groups collaborate in the provisioning of context-aware services [23]. Three components can be distinguished in this architecture: third party services, the WASP platform and Context-aware applications. Third party services Third party services are (web) services offered by parties other than the WASP platform. Different third party services are distinguished [23]:

19 3G Network Services Mobile operators offer services on the mobile network that provide network access capabilities; for example user identification, charging, call setup, messaging et cetera. These services (network capabilities) are accessible through web services. Business Services (offered by Service Providers) Business Services Providers offer content and services for applications build on the WASP platform. For example a hotel reservation service offers the content (information about hotels and their reservations) for a mobile application. Context Services (offered by Context Providers) The context of a user is provided to the WASP platform by Context Providers. Furthermore, they can give a user s information like a personal shopping list or personal schedule. Also, information that is not relevant to one user in particular (but to a group of users) can also be provided by these services. In some cases context information is provided by 3G Network Services. For example, the location of a user can be provided by the mobile operator, by means of a 3G Network Service, when the location of the cell phone of the user is used to determine the location of the user. The location providing services currently available in the WASP platform are: 1. Adding a GPS receiver to each mobile device; 2. Mobile network (operator) based location providing (using network cell identifier); 3. Simulating the location; 4. Mobile network based location providing without intervention of a network operator (see WASP and this assignment). The WASP Platform The WASP platform consists of different components together forming the system environment for context-aware applications. These different components are [23][24]: The request dispatcher The request dispatcher is responsible for forwarding requests from the user to the 3G network. This allows users to switch transparently between different network operators or use different messaging services. The notification manager This component provides functionality for applications to subscribe to and receive notifications when the context of a particular user changes. For example if a user moves, his location will change. The notification manager will notify the application of this change in location. This allows the application to provide context-aware services. The context manager The context manager is responsible for retrieving information about the user s context by contacting appropriate context providers. Therefore it should aggregate the context or derive new context using domain specific rules (for example the speed of a user can be determined using distance and time interval and using this speed and the location one can derive if the user is walking on a street or driving through a street). The context manager is also responsible to update the notification manager on changes in the context. The service registry This component functions as a repository containing information (service descriptions) about the services provided by the third party and context services. This enables searching for required and/or relevant services. The matchmaker The matchmaker uses the services registry to discover the service that matches the request from an application. The results of such a discovery are forwarded to the context-aware application

20 The matchmaker forms, together with the service registry, the service discovery mechanism in the WASP platform. The Context-aware Application The WASP platform offers a framework supporting the creation of mobile, context-aware applications. WASP supports the creation in the sense that the applications can be positioned on top of the WASP platform and make use of the capabilities of the platform [23]. Within the context-aware application, different components can be distinguished [23]: The interaction manager The interaction manager functions as the bridge between the user and the application. The user interacts with the application using this interaction manager. Examples of these interactions are: service request, network switch request, call setup et cetera. The service retrieval & personalization This component is responsible for forwarding discovery requests to (and receiving the result from) the platform (the matchmaker). Moreover, the service retrieval component is also responsible for applying a personalization step defined in the personalization component [25] (e.g. score/sort the results based on predefined and/or historical defined user interest) WASP in practice The WASP services platform was completed in April Different applications have been developed using the WASP platform as a framework. One of the context-aware applications that is deployed on top of the WASP platform is Tourist Compass [24]. It was developed in the WASP project to experience using the WASP platform from both a developer and a user point of view, but also to research how users feel about applications that uses context information to enhance the provided service. The developers stated that context-awareness provides added value in certain cases, but they also warned that caution should be taken when developing context-aware applications, as people are unfamiliar with this (improved) level of intelligence in applications. In the development of the WASP platform, several challenges were not explored by the design, including security and privacy, scalability and performance, and charging. This means that the WASP platform still needs to be completed to be used commercially, on a large scale and in public networks [2] WASP and this assignment The WASP platform was developed by several parties, including the Telematica Instituut. This platform should facilitate the development of the location-based game. This will show if the WASP platform is capable of reaching its goals. And secondly, it could also point out some flaws in the WASP platform, thereby allowing improvement of the WASP platform. Moreover, the WASP platform was recently extended with a positioning technique that retrieves the current network cell on the mobile device itself. Without any intervention of a mobile operator, the location of a mobile device can be determined. This mapping is made possible by actual, onlocation, linking of network cell identifiers to coordinates of a GPS receiver. However, this positioning technique was never really used in practice. The location-based game will therefore contribute to the WASP platform by determining the usability of this positioning technique in its current state

21 3.2. MobiLife MobiLife is another project in which the Telematica Instituut takes part. Section introduces the project. Section describes the importance of context-awareness in this project and section relates this project to this assignment Project Summary The MobiLife project and the WASP project are completely different projects in terms of size, scope and parties involved. The WASP project was a national project of about 20 months with three participants (the Telematica Instituut, the University of Twente and Ericsson) working together to develop a services platform. MobiLife, however, is a European project, consisting of two phases of 28 months, of which the first just started (September 2004). MobiLife, coordinated by Nokia, will be carried out by 22 organizations from 9 EU countries. Besides Nokia and the Telematica Instituut, other participants are for example Ericsson, Alcatel, Hewlett Packard, Motorola, Siemens and DoCoMo [18]. MobiLife results will contain more than just a services framework. As stated in the introduction of this chapter, the strategic goal of the MobiLife Project is to bring advances in mobile applications and services within the reach of users in their everyday life by innovating and deploying new applications and services based on the evolving capabilities of 3G systems and beyond [17]. The MobiLife project also formulated a research challenge: to address problematics related to different end-user devices, available networks, interaction modes, applications and services. MobiLife states that future environments, caused by ICT convergence, give new possibilities, but also new challenges due to increasing heterogeneity, user needs and expectations [17]. MobiLife is built around three main Focus Areas [17]: Self-awareness This focus area provides support for the automatic configuration of devices, services and local connectivity in the user s local environment. Moreover, it enables automatic and multi-modal interfaces that enhance the user experience and minimize the active user effort needed in managing the local environment. Group-awareness This area includes context and presence support to enable individuals to relate to, share, and interact with each other and common artifacts. Novel privacy and trust models are addressed to provide the users with trustworthy services and applications. World-awareness World-awareness offers automatic support for seamless access to and delivery of services across different domains that enable individuals to retain the accustomed use of their services, as they move between different environments and infrastructures Context-awareness in MobiLife Within the MobiLife project, standards to describe users and groups more accurately will be developed. By taking many aspects of the social life and the users environment into account a more accurate description can be reached. Therefore context-awareness is a major building block in MobiLife [17] MobiLife and this assignment MobiLife started only recently. This assignment is lined up with MobiLife by adding the requirements of group forming and suitability for demonstration purposes. The first requirement relates to the Group-awareness area of MobiLife. The second requirement relates to the

22 possibility of the game developed to function as an example of context-awareness and Groupawareness in practice

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24 4. Current work 4.1. Introduction This chapter presents an overview of current work on location-based gaming. Different locationbased games will be described in section 4.2. A comparison between the different games is made in section 4.3. Section 4.4 provides some information on location-based platforms that are used to develop or provide location-based games Location-based Games In July 2004 a list of location-based games was published in Bauwelt, a German architecture magazine [26]. This list is used as a starting point for the description of current work on locationbased gaming and is completed by location-based games found on the Internet and in literature. Single player location-based games, and games that do not map the physical location of the player to a certain virtual world are not included. In these cases the (research) findings are not relevant and therefore they are considered to be outside the scope of this research. The given overview of location-based games is rather extensive. The paragraph can be skipped without damage to the overall understanding of this thesis. Pac-Manhattan [27] Pac-Manhattan places the original game of Pac-man on the streets of New York City. It was developed to explore what happens when a computer-game is placed in real world. A player (Pac-man) runs around the streets to collect all the virtual dots on the streets, while being chased by 4 human ghosts. During the game, each players is linked (by cell phone contact) with an operator who has an overview of the complete game map. Pac-Manhattan could be considered as a location-based game according to the definition, but does require intervention of humans to update the location of the players. All players on the street tell their operator at each intersection where they are. The operator then updates the software. The developers gave two reasons for not using GPS. First GPS does not work well in an urban environment, second the GPS equipment was too expensive. Other positioning techniques are not discussed. I Like Frank in Adelaide [29] According to the authors the first 3G mixed reality game (in March 2004), I Like Frank in Adelaide is a game in which online players from all over the world and players on the streets of Adelaide, Australia, cooperate to search for Frank. Only limited information about I Like Frank is available. No information about positioning mechanisms, why it was developed and the findings of the game could be found, although user positioning was probably achieved by the messages exchanged between the street player and the player on the Internet Pirates! [28] The Pirates! Project, by Nokia Research Centre and PLAY, was developed to explore some future directions of computer game design and game play, and to demonstrate novel gaming concepts and implementations. The players location is used to create an enhanced game experience regaining some of the social aspects of traditional game play in a computer game. While players roam the real world, they are virtually sailing a ship on the ocean. Game objectives include solving different missions such as: finding treasures, trading and fighting battles. Pirates! is a multi-player, computer game for handheld devices connected in a wireless local area network (WLAN) environment. In addition, each device is equipped with a custom-built sensor,

25 which is used to infer the players relative proximity to each other, and to locations in the physical world. Some preliminary user feedback is available. The majority of the players enjoyed the game play. Direct player-to-player contact was evaded because players always risked a Game Over. Some players expressed that they would have wanted to interact more with users, without a direct risk on a Game Over. Another remark was made about the sounds used to alert players of certain events. Sounds alone are not sufficient because they cannot be heard in a noisy environment [34]. CitiTag [30][31] CitiTag is a tag-game where the players are visible on a virtual map of the game area. It was developed to research social experiences and group play in public spaces, based on the awareness of other peoples presence, through the use of mobile technology. In CitiTag players roam a public space with a GPS- and WiFi-enabled handheld device to search for players of the opposite team that they can tag. The player can also get tagged himself if one of the opposite team gets too close to you. Once tagged, a player needs to find a friend to free him. Positioning of users is done using GPS. Results of a pilot trial were rather positive. Players enjoyed the game experience as a result of the presence awareness aspect in this game. Undercover [32] In Undercover players (agents) try to locate and eliminate terrorists. Undercover is a locationbased game developed for commercial exploitation. Undercover is a multi-player, location-based, action strategy game for mobile devices, which allows players to interact with other agents in distant cities or countries. Tasks and game objectives include locating terrorists and attacking the enemy with your choice of weaponry. Undercover provides some group forming functionality. Agents can join in a group to all together attack an enemy. Undercover can be played by SMS or by JAVA (over GPRS). The costs from using SMS or GPRS are the total costs of playing Undercover. The mobile network operator should provide the game in order for its subscribers to play the game. Positioning is done using the cell id of the cell phone. Knowing that an agent is in a certain area is enough for playing Undercover. Uncle Roy All Around You [33] In this game players on the street and online players cooperate in search of Uncle Roy. The last game of Uncle Roy was played in June Only limited information about Uncle Roy is available. No information about positioning mechanisms, why it was developed and the findings of the game could be found, although user positioning was probably achieved by the messages exchanged between the street player and the player on the Internet. Street players used handheld devices to search for Uncle Roy, using a map of the city and incoming messages to move through the city. Online Players cruise through a virtual map of the same area, searching for Street Players to help them find a secret destination. Street players are able to help online players in retrieving postcards from secret locations, online players are able to help street players to look for Uncle Roy. This two-way dependence requires street and online players to team up. Can You See Me Now? [36] Can You See Me Now? is a game that happens simultaneously online and on the streets. The game was designed to explore game experiences in which mobile participants collaborate with those who are online [35]. They focused especially on:? The impact of GPS inaccuracy on the use of location as key component in the game play? The significance of other sources of information, especially real-time audio? Strategies used by participants to achieve successful collaboration? How developers can respond to these issues and support these strategies

26 In Can You See Me Now? up to twenty online players were chased across a certain city by three runners. The online players played in a virtual map of the city. The runners however, were moving through the actual city, connected to the game by a handheld device with GPS and WLAN. The runners were interconnected by an audio channel, which was also broadcasted to the online players. Can You See Me Now? was developed for evaluation purposes. After evaluation, the overall impression was that the game was broadly successful. GPS was, as expected, quite inaccurate, especially in dense areas. This resulted in that runners were shown on the virtual map on different locations than their psychical locations, which also led to unfeasible jumps across the map when the GPS location was accurate again. The real-time audio heightened the tension for the online players (they heard the runners talk about them). It also provided some context information (runners talking about having to wait for traffic on the roads, or hearing the runners breathing heavily when running). This enabled the online players to come up with strategies. Two approaches to dealing with uncertainty were proposed; hiding the uncertainty so that users are not aware of the effects of the uncertainty and revealing the uncertainty to enable users to work with it [37]. Mogi, Item Hunt [38] Another commercially available location-based game is Mogi in which players move outside, pickup virtual items through their mobile phone (when they are near enough) and trade with other players to complete collections (also when both players are near enough to each other). The goal of the game is to get maximum points by completing collections. The game is both accessible through the web and the mobile phone. Web players have a better overview of the virtual map, which enables them to help mobile players finding certain items. All users have to pay a monthly fee to play the game. Moreover, playing the game will generate GPRS data transfer, which will also costs the player some money, although Mogi claims their game is very light. Two positioning techniques are available. GPS is recommended when players are hunting specific items, otherwise cell id positioning (free) is recommended. The game is currently available in Tokyo, Japan (since April 2003). GunSlingers [39] GunSlingers is the next commercially exploited location-based game, this one in Singapore. GunSlingers is a multi-player network game where players move around, track and engage enemies within their vicinity. Positioning is done by the mobile network, thus based on cell id and triangulation, and therefore the game is only available to subscribers of one operator (SingTel). This way only a cell phone is sufficient to play. Any cell phone can be used as a SMS version is available (a JAVA version is available too for more advanced cell phones). Costs are made per SMS (SMS version) or a monthly fee (JAVA version). The players can log in to a website to buy equipment and weapons with the money they earned on their missions. BattleMachine [41] BattleMachine is a commercially available game from a Danish company Unwiredfactory [40]. Players physically move around and battle for areas. Players themselves and the service operator can create unique battles in which other players can compete. It uses the mobile network to position the players and it is available through SMS and WAP and has a web interface. BattleMachine was played in Denmark and Germany. TreasureMachine [42] TreasureMachine is another game from the Danish company Unwiredfactory [40]. In TreasureMachine players try to find a treasure. By clues the players are led to a predefined location where the treasure is hidden. It uses the mobile network to position the players and it is available through SMS and WAP and has a web interface. It is unknown if TreasureMachine has ever been available to or played by the public

27 BotFighters [44] In BotFighters players design a robot online and battle against others on the streets. It is a commercially available game, currently deployed by mobile operators in Sweden, Russia and China (also played in Finland and Ireland). BotFighters is an action game with a robot theme, and it takes place out on the streets in the real world. Players locate each other with their mobile phones, move physically to get within range and then duel by shooting at each other [45]. Mobile positioning is used to determine whether the users are close enough to get a good hit. This positioning is achieved through the mobile network (cell id), therefore only subscribers of the same mobile operator can play together. The game is played using SMS or JAVA/GPRS. Currently it generates over 1 million SMS per week. Supafly [46] A location-based virtual soap opera where intrigues, gang conflicts and romance are the tools of the trade for becoming a virtual celebrity. Just like in BotFighters players start with creating their own character. In Supafly the character will grow and develop a unique personality. The game is location-based, the character will find nearby friends and possible even a date. This game is from the same company as BotFighters. Positioning is achieved through the mobile network (cell id), therefore only subscribers of the same mobile operator can play together. The game is played using SMS or JAVA/GPRS. Geocaching [47] Geocaching is the most widespread location-based game, being available in more than 200 countries. It is location-based in the sense that players look for a hidden treasure using their GPS device and GPS coordinates. Everyone can start a hunt. They just have to hide a treasure, determine the coordinates and come up with a story or some clues. Geocaching does not rely on game logic or on a mobile network. GPS is worldwide available and Geocaching only provides an online portal for Geocachers to get in contact with each other and to exchange information about the caches and their history. Human Pacman [48] Human Pacman is another attempt to bring the traditional game of Pacman to the real world. It was developed to bring the computer gaming experience to a new level of emotional and sensory gratification by embedding the natural physical world ubiquitously and seamlessly with a fantasy virtual playground. In Human Pacman the pacman and ghosts are replaced by human players. Players are equipped with GPS devices and inertia sensors (to track players perspective). The cookies are virtual, but some objects from the traditional game have a tangible representation. All players are linked with a helper who supports them in roaming the virtual world. Human Pacman is thoroughly evaluated [49]. Their findings indicate that users like the idea of Human Pacman as a whole. The tangible aspects (objects) and physical aspects (catching ghosts) of the game are really appreciated (especially the physical aspect). The size of the wearable computer should however be improved as should the accuracy of positioning (to collect the virtual cookies). Helpers are thought to make the game too complex. To explain this sentiment better, more specific research will be conducted. Swordfish [50] Swordfish is said to be North America s first GPS cell phone game. In Swordfish the world is a virtual ocean and cell phones are fishing rods. Swordfish is commercially available on the network of mobile operator Bell (Canada). Players scan for and locate virtual schools of swordfish. Players must move to where the fish are located. Then using their cell phone as a fishing rod, they try to hook and land the big ones, and compete with other players to make the national high score leader board. Swordfish uses A-GPS for positioning

28 Real Tournament [15] In Real Tournament two teams each try to capture as many monsters as possible in a predefined game arena (for example a park). Real Tournament was developed by the Mobile IPv6 Systems Research Lab. This lab tries to gain knowledge of the requirements of future mobile applications. In the case of Real Tournament the focus was on real-time interaction. Real Tournament is a multi-player location-based mobile game, which uses handheld computers, GPS devices, WLAN and electronic compasses (the GPS devices were used for positioning). Results of trials showed that the users enjoyed the gaming experience and had no trouble relating the physical movement with virtual movement. The developers also noticed that players almost immediately wanted to shoot at each other (not only at monsters). This kind of direct interaction between players was not implemented. To provide some possible larger game arenas, GPRS was tested instead of WLAN, but as became clear, GPRS performance is insufficient for real-time gaming. The accuracy of GPS should also be improved. Backseat Gaming [51] The Backseat Gaming project is aimed to explore how to make use of mobile properties for developing compelling and fun game experiences. In this project a prototype game was developed for use by a young car passenger while travelling, thus a highly mobile environment. The prototype was connected to a certain road where, while travelling over that road, the player is (virtually) guided by a dwarf through a dark forest inhabited with evil ghosts. A handheld device is used in combination with GPS (for positioning). Some initial results of the Backseat Gaming project show that young children (ages 5-10) differ in the way they appreciate different aspects of the game [52] Comparison In the previous section a number of location-based games were discussed. In table 4.1 these location-based games are compared. Location-based game Research or commercial ly available Positioning technique Game area Pervasive game Ubiquitous game Augmented reality Pac-Manhattan R By hand Fixed I Like Frank in Adelaide R By talking Fixed Pirates! R Proximity Fixed CitiTag R GPS Fixed Undercover C Cell ID Mobile Network Uncle Roy All Around You R By talking Fixed Can You See Me Now? R GPS Fixed Mogi, Item Hunt C Cell ID, GPS Mobile Network GunSlingers C Cell ID Mobile Network BattleMachine C Cell ID Mobile Network TreasureMachine C Cell ID Mobile