Games provide entertainment or amusement. The strategies learned in games generally have application in real life. The element of surprise sometimes changes the nature of a game.
In the book The Art of Reasoning, David Kelley 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". War games and sports are often not played for entertainment but to build skills for later use.