A JavaScript game library to quickly develop board games for the web
Realtime 3D engine for game development
3D .NET engine for Windows, Linux, Mac
BxEngine For Marmalade And QT
The solution to all your problems
C-Lesh is a game programming language for 2D games.
LEGADEE (LEarning GAme DEsign Environment)
A generic framework for the generation of game levels.
Java based Open source Voxel Engine for RTS games