Arianne is an engine to develop multiplayer online games like Stendhal
GGMud is a cross platform modern MUD client.
PHP WOW Battle.net Armory Raider
CoffeeMudForAI is plaform to design AI in
Scriptable GTK based Python MUD Client
3d peer to peer chatroom where associated pairs of text gravitate
Free MMORPG Engine. Develop and host graphical browser-based games.