From the introduction: In order to play this game, one person must be the referee, known as the Games Master or GM. The others take the part of players. There should be at least two players (a number between three and six is probably best). Each player has a character – a persona or alter ego. It is a player’s task to act the part of, or roleplay, his character. The GM describes each character’s surroundings; that character’s player imagines the scene and how his character would react in such circumstances. The player then explains to the GM the actions that he wants his character to take. Apart from describing the world in which the game takes place to the players, the GM also acts as a referee. She decides if the actions described by the player are possible or not and, where multiple characters’ actions conflict, the GM acts as a judge, deciding who acts in what order and who succeeds and fails. So why is role-playing entertaining? For a player, the fun comes from being able to act the part of an individual with totally different abilities, personality, past and future. For the GM, the fun comes from managing the infinitely varying and unpredictable interactions between the players’ characters and the new world she creates.