I’m currently working on a small ray traced game which uses an open source CUDA ray tracer (tokaspt).
The CUDA renderer is using an advanced form of ray tracing, called path tracing, to achieve photoreal graphics with global illumination. For this the renderer has to shoot lots of rays per pixel, which is computationally very expensive.
The original idea for the game was to create a photoreal 3D version of Pong, but I have a lot of other ideas right now.
There is more info and videos about this game at my blog (Ray Tracey blog). Source code and executables can be downloaded at http://code.google.com/p/tokap-the-once-known-as-pong/
There are currently no physics in the game yet and I’m looking for someone who has experience with integrating a physics engine (PhysX, Bullet Physics, …) into a renderer who can help me. Please send a PM if you’re interested.