Desktop/Android/HTML5/iOS Java game development framework
Open Source MMORPG Framework
Orx: Portable Game Engine
Cross-platform 2D and 3D game engine
Free and Open Game Programming Language for Windows and GNU/Linux
Portable game engine with main focus on point-and-click adventures
Build Cross-platform Applications
C/C++ , PHP, PYTHON, 3D ENGINES, CHROME NATIVE CLIENT
Open-source, cross-platform, C++ game engine for creating 2D/3D games
2D game engine for traditional platform games
Open Game Bootstrap
Single-/multi-player card game Mau Mau (similar to UNO®)
Cross platform 2D/3D game engine written in C++11 & OpenGL ES 2/3
Cross platform Game Creation Software
3D Game engine
C++ game libraries plus server.
cross-platform 2d game engine
Cross-platform reimplementation of AMOS BASIC (runtime)
Investigo - DX9 Performance and Debugging Toolkit