MUD/MOO - (Multi-user Dungeon) (Associated with LambdaMOO, MinimalDB, JHCore, Jay's House Moo, enCore, LinguaMOO) - MUD/MOO is a group of role-playing games modeled on the original “Dungeons and Dragons” games.  MUDS have also been used as conferencing tools and educational aids.  A MOO is an object-oriented MUD.