dhewm 3 main repository
Open Source real-time strategy game engine for early Westwood games
A modern, cross-platform Quake game engine based on FitzQuake.
GemRB is a portable open-source implementation of the Infinity Engine
Go 3D Game Engine
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
Improved version of the X-Ray Engine, the game engine
A cross platform Lua based game engine
Free and Open Game Programming Language for Windows and GNU/Linux
2D physics engine for games