A multiplayer game is a game which is played by several players. The players might be independent opponents, formed into teams or be just a single team pitted against the game. Games with many independent players are difficult to analyse formally in a game-theoretical way as the players may form coalitions.
Game theory 
John Nash proved that games with several players have a stable solution provided that coalitions between players are not allowed. He won the Nobel prize for economics for this important result which extended von Neumann's theory of zero-sum games. Such a stable strategy is called a Nash equilibrium.
If cooperation between players is allowed, then the game is more complex. Many concepts have been developed to analyze such games. While these have had some partial success in the fields of economics, politics and conflict, no good general theory has yet been developed.
In quantum game theory, it has been found that the introduction of quantum information into multiplayer games allows a new type of equilibrium strategy which is not found in traditional games. The entanglement of players's choices can have the effect of a contract by preventing players from profiting from betrayal.
Examples of the types of such games include:
- Party games - A social game played with a number of people, little equipment, and simple rules (e.g. Charades)
- Card games - A game played with a deck of cards. (e.g. Contract Bridge)
- Board games - A played on a game board with set rules. (e.g. Monopoly)
- Multiplayer computer games - played either on networked or individual computers
- Multiplayer online games - played over the Internet
- Massively multiplayer online role-playing games - a notable subset of online games
- Multiplayer video games - played on a video gaming system
See also 
- Oxford English Dictionary. Oxford University Press. 2008. "Designed for or involving more than two (esp. many) players or participants"
- K. G. Binmore (1994). Game Theory and the Social Contract. MIT Press. ISBN 0-262-02444-6.
- Laszlo Mero, Anna C. Gosi-Greguss, David Kramer (1998). Moral calculations: game theory, logic, and human frailty. New York: Copernicus. ISBN 0-387-98419-4.
- Simon C. Benjamin and Patrick M. Hayden (13 August 2001). "Multiplayer quantum games". Physical Review A 64 (3): 030301. doi:10.1103/PhysRevA.64.030301
- R. Wayne Schmittberger (1992). New Rules for Classic Games. New York: Wiley. ISBN 0-471-53621-0.