aka ogre v2 - scene-oriented, flexible 3D C++ engine
FlightGear Flight Simulator: free open-source multiplatform flight sim
3D Engine c++
LDraw™ editor for LEGO® style digital building instructions.
Cross-platform 2D and 3D game engine
Realtime 3D engine for game development
Sorry this project is no longer being supported
3D .NET engine for Windows, Linux, Mac
A public domain cross platform 3D game
Get as many FPS as you need and amazing effects by rendering HTML/CSS
A cross-platform game framework based on OpenGL and GObject.
PixelLight is a cross-platform application framework
Game engine supporting many 3D/2D formats and graphic effects