CTFs as you need them
Open Source MMORPG Framework
Arianne is an engine to develop multiplayer online games like Stendhal
PyCAPGE - Python Classic Adventure Point and Click Game Engine
Multidocument automation by templates - for sphinx, mkdocs, epydoc ...
Event driven concurrent framework for Python
3D .NET engine for Windows, Linux, Mac
evolution for vegastrike SpaceSim/Combat/Trade game
Free strategy browsergame engine.
AutoTeach makes kids study and learn in exchange for internet access.
Modular Gaming Open Source Persistent Browser Based Game Framework
Library for creating turn-based games with simultaneous moves.
Open source network game service
Moteur de jeux de rôles descripifs (RP) en PHP
Cross-platform 2D game engine
Game framework on top of Python, Panda3D and Twisted
The Lambda-Engine is a cross platform game engine.