A zero-player game is a game that has no sentient players.
In computer games, the term refers to programs that use artificial intelligence rather than human players.
Conway's Game of Life, a cellular automaton devised in 1970 by the British mathematician John Horton Conway, is considered a zero-player game because its evolution is determined by its initial state, requiring no further input from humans. In addition, some fighting and real-time strategy games can be put into zero-player mode by placing one AI against another.
There are various different types of games that can be considered "zero-player".
Some games, such as Conway's Game of Life, evolve according to fixed rules from their initial setup. Others such as Snakes and Ladders evolve according to chance, but similarly the player(s) have no decisions to make and have no impact on how the game progresses.
A more complex variation on the above is the case of AIs playing a game. Humans may have a challenge in designing the AI and giving it sufficient skill to play the game well, but the actual evolution of the game has no human intervention.