Open source clone of the Age of Empires II engine
Voxel game-creation platform with easy modding and game creation
3D Game engine with editor
Injectable LUA scripting system, SDK generator, live property editor
A free 3D game engine to create games and realtimes scenes for Windows
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
Open-source, cross-platform, C++ game engine for creating 2D/3D games
Open Source 3D Game Engine
A generic 2D engine for any kind of game
3D Game engine
TurboSphere is an easy to learn and powerful JS based game engine.
Cross-platform 2D game engine