A game is an activity undertaken for entertainment or diversion, in which the actions of players are controlled by rules. It is usually undertaken in a structured manner and may have a competitive element, although it can also be a form of exercise, learning, or social interaction. Many games require skill, strategy, luck, or a combination of these; others are purely or solely based on chance, such as card and board games, sports, or dice games. Games can be played by individuals or in teams, amateurs or professionals, and for money or for other benefits such as prestige or achievement. Games can be formal, such as chess or baseball, or informal, such as playground games and imaginative children’s play.

There is no one medium that constitutes a game: they can be played on paper, in a physical space, on computers, or even in the imagination of the player. There is a certain amount of immaterial support, however: the existence of clear rules that limit what can be done in the game, the ability to measure progress towards goals, and the need for players to interact with each other and believe that their interactions are shaped by those same rules. It is possible to create a game without any equipment at all, but most games are designed with some sort of hardware in mind, whether it be a computer, mechanical contraptions, the laws of physics, or a human brain.

The concept of a game can be applied to different areas of life and culture, and has several meanings that are not directly related to playing: If someone says they are “game for” something, it means they are willing to try it out and see how they like it. It is also common to refer to wild animals that are hunted and shot, both for sport and as food, as game.

Despite the wide variety of definitions of what constitutes a game, there are some fundamental similarities: most involve competing against other players, there is a sense that winning is better than losing, and there is an element of chance or luck in the outcome. Some games, such as chess and Go, are purely strategic and require the use of logic and intellect; others, such as children’s games or candy-based games, are more luck-based and do not necessarily demand any skills.

A useful game definition must be relevant to the particular use case, and should take into account previously published work on the topic (e.g. Bogost 2009; Deterding 2013; Esposito 2005; Karhulahti 2015b). It must be clear what the boundaries are between a game and other activities, and where there are ambiguities that need to be resolved. It should not attempt to be prescriptive (what games should be, for all time). Our limited horizons rule out such an ideal. However, it is still possible to make a useful game definition that takes into account these limitations and acknowledges their relevance.