Cross-platform C framework very compact libraries and tools.
A generic 2D engine for any kind of game
AutoTeach makes kids study and learn in exchange for internet access.
C++ game libraries plus server.
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 game development kit for Sifteo Cubes.
2D Game Engine, based on OpenGL and focused on Isometric Games
Extremely simple joystick rumble / vibration library
A graphics engine + toolkit.
3D Web UI, Embed Web and Flash in 3D Games, based on WebKit
Pear3DEngine is a modern and modular 3D development framework
Open Source Virtual World and MMOG Development Platform
cross-platform 2d game engine
Multi-Language Wrapper Collection for the Irrlicht Engine
Sourceport of the classic Descent Level Editor
Game framework on top of Python, Panda3D and Twisted
A cross-platform Java 2D graphics library using OpenGL.