Xash3D FWGS engine
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
3D Engine c++
GemRB is a portable open-source implementation of the Infinity Engine
GLScene Engine for Delphi & C++Builder VCL Windows 32/64
Orx: Portable Game Engine
Cross-platform 2D game engine (+ full OpenGL, +full OpenGL ES )
Cinema Enters Game Console
2D Game Engine
ZED OS the clone of Windows XP
Android OpenGL Game Engine
Character animation system for games and simulations.
Multi-threaded game engine for Android
3D .NET engine for Windows, Linux, Mac
Cross platform 2D/3D game engine written in C++11 & OpenGL ES 2/3
Visual Novel engine, editor and game development.
An Action Adventure Space Physics Game
cross-platform 2d game engine
PixelLight is a cross-platform application framework