Open Source MMORPG Framework
Arianne is an engine to develop multiplayer online games like Stendhal
Java Settlers
2D game engine for traditional platform games
Single-/multi-player card game Mau Mau (similar to UNO®)
Cross-platform 2D game engine
Game framework on top of Python, Panda3D and Twisted
The next generation mud is an open-source extensible, programmable mud
A generic C++ MUD server featuring a strategy-style hexagon map