Proximity gaming, i.e. close-range wireless network gaming, is being enabled by new handheld devices such as mobile phones, the Sony PSP, and the Nintendo DS. This opens up new gaming possibilities, and the combination of proximity gaming and mobility is particularly exciting. Imagine the kind of ad hoc multiplayer games where people suddenly enter each other's games simply because they're in range.
Why Proximity Gaming Is Interesting
Entering a multiplayer game is normally a formal procedure. The player defines their character, selects which game server to join (or sets up a new game), decides who to play with, and so on, before entering the game. The wirelessness of proximity gaming allows for ad hoc multiplayer games, where people suddenly enter each other's games simply because they're in range.
The Japanese Lovegety was a simple yet powerful demonstration of a proximity service: a device that beeps when a potential partner was nearby, based on a set of preferences.
The ad hocs in turn unleashes several interesting game design aspects, for example that clusters of proximity gaming devices create the illusion of a persistent world game, or viral aspects such as "electronic rumors" that are transmitted to nearby players.
Proximity gaming is also considered an interesting area for the latest handheld game devices. When Sony presented the PlayStation Portable (PSP) during Game Developers Conference (GDC) 2004, proximity gaming was mentioned as an interesting field of next-generation multiplayer gaming.
Game Design Aspects
Given the basic concept of proximity gaming, there are several design choices to be made when designing a proximity game. The following chapter discusses a few design patterns to consider.
Formal vs. ad hoc game sessions
Traditional multiplayer games usually follow a formal structure, but an ad hoc game session in a proximity game is where players automatically join the same game session when their devices are within range of each other. A single-player game seamlessly becomes a multiplayer game, and then returns to single-player mode when the connection is broken. Game characters are defined beforehand. Game rules are either fixed, or negotiated between the devices when merging two game sessions.
Connection and disconnection as game event
If players can move around with the proximity gaming devices, players will constantly connect and disconnect from each other. These events can be used in the game design itself, as an indication of a player entering or leaving a certain range.
A simple application can play a sound or show an animation when another player was nearby. More advanced games could change gameplay mode when someone connects, e.g. change from observation mode to battle mode.
Multiplayer games can be designed to allow anonymous players, where players create an avatar, an alter ego, and masking their true identity. Combining this with ad hoc game sessions, this allows for games where you could suddenly start playing with a stranger. The only thing you would know for certain is that the other player is close enough to be in range.
In a setting where there are many people and where appropriate devices are widespread, it can be an exciting part of the game trying to figure out whom you are playing with in real life.
In a traditional multiplayer game, all players normally agree to take part in the game and know the game rules that apply. In a proximity game, the total opposite can be true. One player can actually "invade" another player's game without permission. An example could be to stop by and leave a virtual "graffiti tag" in another player's game, a sort of social invasion.
Distributed game world
In a proximity game, the game world can be distributed across the participating players' devices. With ad hoc game sessions, the game world could then grow or shrink as new players join or leave the game.
Imagine a game where each player has her own pirate ship. Before encountering any other player, the ship floats by itself at sea, and the player can walk around with her character on the ship. When another player is in proximity, another pirate ship appears on the screen. The two players can battle, but also board each other's ships. Every new player means a new ship on the screen, and so the game arena grows with each player. The ship becomes an analogy for the device itself.
One example of a distributed game world is the game Pac-Man Must Die! developed by the Viktoria Institute in Sweden. Players stand close to each other and play the game on wireless PDA's. In the game, the players control ghosts and try to avoid being captured by Pac-Man. The game arena is distributed across the players' devices, and a player can capture Pac-Man by moving away from the other players when Pac-Man is on the screen.
A problem appears when the players disconnect when one player is on another player's "ship". What should happen; should the player return to her own ship, or just vanish into thin air?
Persistency between sessions - pseudo-persistent game worlds
In the case of a distributed game world, the state of the local game worlds can be saved between game sessions. When a player visits another player's pirate ship again, she finds a sword that was left there on her previous visit.
Given enough players, the illusion of a persistent-world game could be created. This "pseudo-persistent game world" would act as a persistent world as in massively multiplayer online games (MMOG's), but in fact be created of lots of fragments of a world. The persistency is maintained through synchronization between two players at a time. This will lead to inconsistencies in the game world data, and these discrepancies must be dealt with in the game design.
Viral behavior and electronic rumors
Proximity gaming, especially in its ad hoc sense, is an ideal ground for viral game behavior. Messages and virtual items can travel between players. Players could "infect" other players that are within range.
Information within the game can be viral, too. If in-game information, such as the state of the game world or the highscore list is synchronized between players upon connection, information spreads from player to player. But as in the classic "whisper game", no player will hold the absolute truth, and the quality of the information is weakened as the distance to the source increases. The more connections each player makes, the more pieces of the puzzle she will have and thus the closer to the truth she will be. That in turn can foster social gameplay.
Involving non-player persons
One extraordinary aspect of viral gameplay is to involve non-player persons in the game. Given that the game device can detect and in some sense identify a nearby person, other people can act as "props" in a proximity game. Non-players can be tagged by players, possibly carrying a virtual infection or a virtual piece of information. The non-players could either be totally unaware of the game in progress, or they could be manipulated by players as part of the gameplay, e.g. coaxed to walk in a certain direction.
Two students at the Swedish Institute of Computer Science used this game design element to design a game for shopping malls. The game, Frog Race, enabled players to use Bluetooth devices to scout for nearby persons that were carrying Bluetooth-enabled phones. When a suitable person was found, the player can attach a virtual "frog" to the person. The frog will then follow the non-player wherever she went. The game objective was to get their own virtual frog out of the shopping mall as quick as possible.
New Types of Network Games
Putting the pieces together, proximity gaming can be used to create new game concepts.
With the Lovegety as basis, it's easy to imagine matchmaking games and services. Create a profile, and the device will notify you when someone matching the profile is nearby. The Lovegety was a pretty simple device, and a game could involve more role-playing elements and allowing the player to create a more detailed profile of herself. Such services rely on a large community, and therefore mobile phones is a suitable platform.
Sports and other physical games are excellent applications of proximity gaming. With the players moving around, proximity is a way to detect other players and possibly parts of a physical game arena. It's easy to imagine an orienteering game, where players would have to move around and find navigation points powered by Bluetooth transmitters or similar. But other forms of electronic sports are also feasible, including ball sports (with a virtual ball).
In a pervasive game, a game that blends with the player's real world, the game device would rather take the role of a "tool" in a real world setting, than being the scene for the game itself. Such a game benefits from the viral aspects of proximity gaming, for example to send secret pieces of information between agents.
An example would be a game about a viral outbreak. The virus is virtual, and spreads from person to person as soon as they are within range. Even non-players could be carrying the virus. The players have the "tools" (i.e. game software) necessary to track and destroy the virus. But since the virus spreads in the real world, the players have to find the people carrying the virus and maybe ask former "patients" about their whereabouts in order to track the source of the virus.
Case study: Proxiball
Proxiball was designed to be a small demonstration of a proximity sports game. The basic concept was "virtual rugby", a team-based game where the objective was to deliver a virtual ball to a virtual goal. There was no ambition to create a commercial product of this concept, merely to use it as a research platform for other proximity gaming concepts.
The interface was designed to be extremely simple and quick to use, since this is a physical sports game where players can spend limited time looking at a screen. Each participant has a device of her own, and another two devices are used as goal cages. There are two teams; blue and red, without restrictions on the team size. The game interface shows the player in the centre, with nearby team members in the bottom half of the screen and nearby opponents in the top half of the screen. Selecting another player and pressing the fire button passes the ball, or try to steal the ball if it was held by the selected opponent.
The devices acting as goal cages are running the software in a special mode, where it counts the number of times it has received the virtual ball (i.e. when someone has scored a goal). The goal cages automatically give the ball to a member of its own team after a goal.
As test platform, Nokia Series 60 phones were chosen. The game application was implemented in Java (J2ME) and Bluetooth was used as communication protocol.
The Bluetooth programming interface is event driven and supports events for when a new device is found. However, it does not have an event for when a connection to a device is lost. Since Proxiball relied on both events, custom code was added to create a "memory" of nearby devices and to trigger events when a device lost connection.
Testing turned out to be a big problem, since the actual Bluetooth implementation on the mobile phones turned out to act quite differently compared to the emulation on PC. The hardware implementation only supports one connection at a time, so the game's communication layer had to be rewritten to do the communication in a serial, "one-step-at-a-time" manner.
For testing the first version of Proxiball, four people from the author's office were selected. With two additional phones as goal cages, a total of six phones were used. The goal phones were put on tables roughly 50 meters away from each other.
A phone used as the Red Team's goal
The four players gathered in the centre, right between the two goal cages, and the game started. As the application started up on each phone, the virtual ball flicked from screen to screen when the phones synchronized their connections. When it finally stabilized, the ball ended up in the phone of a surprised member of the red team. He ran to the blue goal and scored a quick goal before anyone else could react. The blue goal played a sound effect of a fanfare. 1-0.
The ball was handed to a blue team member who now was nearby. He started moving towards the red goal, but suddenly the ball was snatched by the red player and another goal was made! 2-0.
Blue player moving in to the goal area
Now, the blue players grouped and started running in a wide arc around the office, quickly passing the ball back and forth. They approached the red goal, now guarded by both red players. Intense button-jabbing followed as the blue players tried to score a goal and the red players tried stealing the ball. Suddenly, the fanfare sounded from the red goal phone. 2-1.
Proximity Gaming in 2010
So, will proximity-based games be a new game genre of its own, dominating the video game shelves in five years? No, proximity gaming - compared to massively multiplayer games and pervasive games - will not be coined a game genre in its own right. Instead, elements of proximity gaming will seep into the design of mobile and handheld games, little by little.
Two things hamper the development of proximity gaming applications: penetration of game devices that can communicate with each other, and social acceptance of "invading" other peoples' personal space in a game. But changes are on the horizon, and these two elements are tied to each other, pulling the other forward.
Pervasive computing is no longer a vision - it is already here. People carry around plenty of small computer-powered devices: mobile phones, PDA's, digital cameras and music players.
The next logical step is to get all these devices to work together. "Connectivity" will be the predominant feature of many consumer devices; not only mobile phones and handheld devices, but also music players and toys. These devices will connect with each other for improved integration, but also with other peoples' devices to exchange information, as well as for pure entertainment value. A recent example is Konami's music toy Otoizm, which remixes your portable music, and also shares music with other Otoizm users that happen to be nearby.
In short, people will grow more accustomed to sharing information, and interacting with nearby people in a connected manner. Their definition of privacy will be reshaped and redefined. As that happens, game designers will feel more confident in adding proximity gaming features to their games. And wireless gaming will never be the same again.
[Tom Söderlund currently works with mobile business development at Oberon Media, a provider of casual games. In 2000 he co-founded the games studio It's Alive, known for location-based game BotFighters, and has worked as Head of Games Publishing at the mobile games publisher Blaze, and as Executive Game Producer at the games publisher Daydream.]