I wanted to hold off on releasing anything publicly until I had a little more done, but I guess now is a good time a time as any.
I've been working on a 3D engine for the Xbox that supports quake3 formats for shaders, models, and levels. Like DXQuake, this engine is not in fact the quake3 engine and is not based on the source of the quake 3 engine, and like DXQuake I've written this engine entirely from scratch and until now this was the first I ever heard of DXQuake.
However, unlike DXQuake, my engine is actually written 100% for xbox and includes many xbox exclusive engine features that would actually making porting back to PC impossible. Just as one example, the implementation of Q3 shaders dynamically recompiles directly to Xbox pixel shader microcode, which 99% of shaders renderable in only 1 pass. The rendering performance has been optimized in a large number of ways for the xbox architecture as well, including a large preprocessing stage of input geometry and BSP cluster cleanup for maximum rendering performance on the Xbox. There's no problem rendering 4 player split-screen even with many models on screen at a full frame rate. The engine also uses an internal caching mechanism in the resource management system that makes use of the Xbox hard-drive to get around memory limitations caused by the lack of a kernel-managed virtual memory system.
That said, there is still quite a bit of work to do, but right now I'm guessing I could make a release within maybe a little over a month which would include the engine source if anyone else was interested in making their own homebrew games with it.
I'd like to stress once again that the engine is not the quake 3 engine and is only designed for creating high quality Xbox homebrew games. Although the game I am working on using the engine is going to be an FPS, it is not going to be quake 3. I believe the xbox-scene focuses too much on ports on not enough on original content.
Anyways, here are some relatively recent screenshots (on xbox) showing what the engine can do so far.
(IMG:
http://friesen.wafflemind.net/projectx11.jpg)
(IMG:
http://friesen.wafflemind.net/projectx12.jpg)
(IMG:
http://friesen.wafflemind.net/projectx13.jpg)