Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
Real Time Strategy game engine supporting early Westwood classics
GemRB is a portable open-source implementation of the Infinity Engine
A modern, cross-platform Quake game engine based on FitzQuake.
Game engine supporting many 3D/2D formats and graphic effects
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
DOOM / Heretic / Hexen source port with enhanced graphics and UI
Improved version of the X-Ray Engine, the game engine
KlayGE is a cross-platform open source game engine
A mobile game distributed server implemented using netty4.X
Paintown is a 2d fighting game engine.
2D physics engine for games