3D engine with modern graphics
A layer built on top of the Insight Toolkit (ITK)
3D Procedural Modelling and Procedural Texturing Tool in OpenGL/C++
Cross-platform 2D and 3D game engine
action/combat flight sim
sauerbraten with LuaJit2 scripting
Pear3DEngine is a modern and modular 3D development framework
A 3D rendering / entity engine