Complete Text of the Game Rules:
One participant is chosen to be the Game Master (GM). The others are all players, and must make characters. The GM is responsible for designing an environment and situations with which the characters will interact, and to approve the players' characters. The GM has final say over everything that happens in the game, but players who don't like it are allowed to quit.
Before play begins, the participants should choose a setting. The setting might be cyberpunk, fantasy, Russian Revolution, ice age, English Civil War, or anything else the players can imagine. The characters and environment made by the players and GM should be consistent with the setting.
Players may use any media they wish to describe their characters; pictures, short stories, clay, etc. Some players may present characters made under other rules systems. Players should be prepared to clarify their characters for the GM. The GM will decide whether or not the character is reasonable, and may give suggestions for revisions or disallow the character.
As the game progresses, it often becomes plain that a character is not complete. Some aspects of a character were not made clear in, or mentioned by, the original character concept. Sometimes such changes do not represent oversights in character creation, but rather changes which the character has undergone over the course of the game.
With the GM's permission the character concept can be updated or modified. In some cases, a player may petition for such a change. To prevent character development from distracting players from the game, many GMs will only entertain suggestions to modify a character concept at the end of a game session.
Game-play consists of hypothetical situations being described by the GM, and the characters' actions and reactions being described by the players. The GM describes settings in which the characters find themselves, including the actions of any characters in those settings not represented by the players.
The GM will sometimes use (or ask players to use) a random or pseudo-random influence, to help determine the outcome of particular actions. The GM may specify the random factor (GM's whim, tarot cards, question to a passerby, vote, dice, a spinner, random number tables, bribes to the GM, expenditure of chits or points, acting out the scene, rock-paper-scissors, etc.), or allow the player to choose. The GM interprets the result.