A 1973 MUD (with map!):
“more like a MUSH (“Multi-User Shared Hallucination”) with one user at a time, specifically…”
The system is very clunky (although to be fair, the first of its kind). You must type WRITE, MOVE, BUILD, DIG, or OUT in full to do a command. WRITE lets you add to the text of a room. MOVE gives a list of adjacent rooms; if only one room is adjacent, you are moved there automatically. BUILD lets you make a brand-new room that is linked to your current room, and DIG lets you make a new tunnel into an existing room (which requires you type the exact name of the existing room you’re thinking of).
Play online at the IA: