3D game engine/framework in C, with Luajit and Python bindings now
Game engine supporting many 3D/2D formats and graphic effects
GemRB is a portable open-source implementation of the Infinity Engine
Portable game engine with main focus on point-and-click adventures
A 3D game engine in java.
An advanced flexible game engine for Java.
A 2D Adventure Game & Engine
A 3D, fully concurrent game engine
The Lambda-Engine is a cross platform game engine.
Game engine supporting many 3D/2D formats and graphic effects