This video demonstrates the Blender Real Time Engine in conjunction with Bullet Physics. I hope it is a fair approximation of UMMO potential engine capabilities. My experience using Peragro on Windows 7 64 seemed to show it to be an extremely fast renderer.
My limited experience with the Blender engine have shown it to be not as fast as CrystalSpace (as a game engine that is). In any event, it is simply the physics and lighting/texturing that should interest here.