Multi User Shared Hallucination (thing)

A Multi User Shared Hallucination, or MUSH, is an text-based online game (like a MUD) where Role Playing is the object. Plotlines and storylines are created by the admin and the players, and worked on (ideally) in a cooperative manner. Some games of this type (and it's kin, MUX) are AmberMUSH and ChivalryMUX