Unity3D Client And C# Server Framework
CTFs as you need them
Game engine supporting many 3D/2D formats and graphic effects
Arianne is an engine to develop multiplayer online games like Stendhal
PyCAPGE - Python Classic Adventure Point and Click Game Engine
Java Settlers
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
Example code for creating a 2D platform game in Java.
Multidocument automation by templates - for sphinx, mkdocs, epydoc ...
C/C++ , PHP, PYTHON, 3D ENGINES, CHROME NATIVE CLIENT
Event driven concurrent framework for Python
evolution for vegastrike SpaceSim/Combat/Trade game
AutoTeach makes kids study and learn in exchange for internet access.
A mobile tower 3D tower defense/defend the flag game
A world editor for HGE game engine written in python and uses OpenGL.
Pygrid is an open-source and cross-platform pygame/python 2D engine.
A graphics engine + toolkit.
Sprite Font Creator
An extensible development framework for roleplay games.
Open Source Virtual World and MMOG Development Platform