Players of this type of role-playing game play as imaginary characters that go on heroic adventures. The characters can be many types: a strong warrior, a wise wizard, a skilled thief. One person in the group acts as a moderator, or referee (called the "dungeon master," or DM, in Dungeons and Dragons and "game master", or GM, in other games), of the game. This person is responsible for making sure there is a fair use of the rules and is often also in charge of designing fun, interesting adventures for the other players.