that such games do not constitute a game, because they lack any element of competition. He asserts that such zero-player games are nonetheless games because they are used recreationally. Another method, developed by Wright, divides games into the following categories: educational or informative, sports, sensorimotor (e.g. action games, video games, fighting and shoot 'em up games, and driving and racing simulators), other vehicular simulators (not covered by driving and racing), strategy games (e.g. adventure games, war games, strategic simulations, role-playing games, and puzzles), and "other". A third method, developed by Funk and Buchman, and refined by others, classifies electronic games into six categories: general entertainment (no fighting or destruction), educational (learning or problem-solving), fantasy violence (cartoon characters that must fight or destroy things, and risk being killed, to achieve a goal), human violence (like fantasy violence, but with human rather than cartoon characters), nonviolent sports (no fighting or destruction), and sports violence (fighting or destruction involved). Classification by causes of uncertainty Games can be categorized by the source of uncertainty which confront the players: Chance Combinatorics (a large number of sequences of moves) Different states of information among the players (each player knows only his own cards) Based on these three causes, three classes of games arise: Combinatorial games Games of bluffing and strategy Games of chance Game theory Game theory classifies games according to several criteria: whether a game is a symmetric game or an asymmetric one, what a game's "sum" is (zero-sum, constant sum, and so forth), whether a game is a sequential game or a simultaneous one, whether a game comprises perfect information or imperfect information, and whether a game is determinate. See also Entertainment Software Rating Board Game of skill and Game of chance – another classification scheme Video game genre References Further reading Game terminology Classification systems by subject