Live-action virtual reality game

Live-action virtual reality games is a genre of digital games that combine live player action, mixed-reality, sensors, actuators, context-awareness, and several interaction paradigms such as tangible objects and full-body interactions (e.g. gestures and movements). In these games, players wear head-mounted display devices (HMDs) and see a virtual world in first person perspective. The virtual world is constructed using a physical world structure as the basic blueprint. The game keeps both worlds superimposed, which means that the players walk in the real (physical) environment acting out their avatars while seeing only virtual objects.

Players interact with the game using different interaction paradigms (e.g. tangible interaction, gestures, embodied interactions). This setup enables players to touch the physical environment (such as walls and the floor) and other physical objects, "feeling" the mixed-reality environment. Physical objects that reside in the physical world are also mapped to virtual counterparts.

Main concepts

Live-action virtual reality games create a mixed-reality termed "the game stage". The game stage comprises a virtual world overlapped with physical world information. The virtual world is modelled using the physical world architecture. For example, if the game takes place in a school floor, the floor structure (walls, doors, rooms) and physical objects that reside in this space are mapped to a 3D virtual world in 1:1 scale. Then, the game keeps the virtual world and physical worlds superimposed. This means that players see the virtual world through HMD devices and may move freely in the physical environment, which enables players to walk and touch the physical objects while seeing their virtual representations.

After creating the virtual world using this primary source of information, the game may add virtual contents to this environment. Finally, the virtual world is augmented with real-world information collected through several sensors. Examples of such information that may be present in these games are:

• Time of the day, weather information, environmental noise, ambient light, humidity, and temperature;
• Player information, such as physiological stage, social network profile, and personal preferences

The game may communicate information to players through wearable devices and environment devices. The environment devices are physical objects placed in the physical environment. These physical objects may be digital or mechanical devices. For example, these devices may output audio, vibrations, and real-world effects (e.g. smells, smoke, wind). Examples of wearable devices are HMDs, headphones, gloves, vests, clothes, and smart bands.

Comparison with other types of games

Early VR games

Earlier virtual reality games focused on immersing the user's visual sense in the virtual world. The users interacted in the virtual environment with limited mobility – walking in the physical space was not possible as the equipment that ran the simulation and the HMDs devices were not portable. Examples of these games were Dactyl Nightmare and Grid Busters by the Virtuality group.

Augmented reality games

A major difference between live-action virtual reality games and augmented reality games is that in the former, players do not see the physical world. In AR games, players see the physical world (through HMDs and other devices) and virtual information placed on top of it. An example of an AR game is ARQuake.

Pervasive games

"Pervasive game" is a broad term used to encompass games that take place in the physical world (outdoor and indoor spaces), exploring mobility, mixed-realities, and context-awareness. There aren’t exact definitions of what constitutes a "pervasive game". Valente and co-authors identify some patterns in pervasive games reproduced below (p. 3):

• The game is constantly coming back to the real-world, which means that the game is played in physical places and it is not constrained to stationary computing devices;
• The physical world (places, objects) is part of the game and it is combined with the virtual world, creating a mixed-reality;
• Mixed reality is always existent and it is created through pervasive computing technologies (e.g., sensors, context-aware systems);
• The spatial mobility occurs in a physical "open" environment, that is, the "game world boundary" is not "well-defined", and sometimes it can be unconstrained;
• The players use mobile devices (e.g., smartphones, tablets, custom hardware) to interact with the game and with other players;
• The game may last for several days or weeks (or more), blending with the daily lives of players. The game may define a persistent world that progresses without player intervention. If some important event happens in the game, the game may notify the player to take action. These aspects are not mandatory;
• The game may focus on focuses on promoting social interaction among players. Social interaction in a pervasive games may happen directly (face to face interaction) or indirectly (mediated through technology). This aspect is not mandatory as pervasive games may be single-player games.

Pervasive games also provide a mixed-reality, but the nature of this mixed-reality is different than the one found in live-action virtual reality games. For example, the mixed-reality in pervasive games is based on the physical world being enriched with information collected through sensors, which may be placed in the environment or carried by users inside smartphones.

Alternate reality games

"Alternate reality games" (ARGs) take place in a surrealistic setting where the game denies its existence "as a game" – the game advertises itself as "this is not a game". ARGs are based on the real world and feature interactive narratives, sometimes being unveiled as massive puzzles that use different media, such as emails, websites, and phone calls. Game masters create (real-world and virtual) content and steer the story according to players' reactions. The game is purposely ambiguous, so that players always question if the game activities are indeed part of the game, or part of real-world life. This includes discovering how to enter the game and guessing if it is over.

The term "alternate reality game" may suggest that players are transported to another kind of reality, which is similar to the ideas of live-action virtual reality games. However, in ARGs, all game activities take place in the real-world and there is no mixed-reality. An example of an early ARG is "The Beast", which was a marketing piece related to the A.I.: Artificial Intelligence movie by Steven Spielberg.

Current implementations

Alexandre Silva and co-authors provided an indoor navigation system for live-action virtual reality games that addresses tracking of physical elements in a room. This system required deploying infrared markers in the physical space where the game happens to enable the game to create a 3D model using the physical structure as input.