All through human history, people have played games. They've done so mostly to entertain themselves and others. Games are a form of self-expression, and also a means of training young people, and of reminding adults of the preferred values of the society in which they live.
Games can involve one person acting alone, but more often involve competition among two or more persons with differing goals. Philosopher David Kelley, in his popular introductory reasoning text The Art of Reasoning, defines the concept "game" as "a form of recreation constituted by a set of rules that specify an object to be attained and the permissible means of attaining it."
This covers most cases well, but does not quite fit with things like war games and sports that are often done not for entertainment but to build skills for later use. In Philosophical Investigations, philosopher Ludwig Wittgenstein argued that the concept "game" could not be defined. Stephen Linhart said, "People say you have to choose between games and real life. I think this claim that there's a dichotomy is very dangerous."
Types of Games
See also: List of game topics, Game classification, Game Theory, Play, Toy