MUD

The generic definition of a MUD is as follows (taken from the more detailed wikipedia MUD definition)

a MUD (Multi-User Dungeon or Domain or Dimension) is a multi-player computer game that combines elements of role-playing games, hack and slash style computer games and social chat rooms. Typically running on a bulletin board system or Internet server, the game is usually text driven, where players read descriptions of rooms, objects, events, other characters, and computer-controlled creatures or non-player characters (NPCs) in a virtual world. Players usually interact with each other and the surroundings by typing commands that resemble a natural language, usually English.

3-Kingdoms is currently running LDMud Version: 3.2.11-dev.710