Yet even they use descriptions of physical objects and places to ground the action. And to that degree they still maintain a connection to the concrete world in the same way that memory palaces used perceived space model conceptual ideas. There is a major difference between MUDs and memory palaces, of course. While memory palaces were idiosyncratic and internal, MUDs are external, shared environments. Conceivably, they are sites of collective memory recalling the accretive memory of CAD models and network news threads.
Movement is categorical, accomplished by typing directions or destinations offered by the game.
Players in the MUD may type 'N,' for example, to wind up in a room immediately to the north. A description presents this new room and its occupants along with suggested exits. Users instantly relocate episodically with a directional command. The experience of MUDding is similar to reading a book. Characters converse in a described setting.