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."
See also sport.