[pure-awesome]

Mud is an odd choice of name for a component of a graphical games engine, given that a MUD is a Multi-User Dungeon: the old-school style text-only MMORPG. (There are still a few active ones such as Alter Aeon and Miriani).

[justaguyinspace]

I immediately thought of MUD's as well. There's an active community on Reddit and still many hundreds (maybe thousands) online and playable!