I've had this idea in the back of my mind.
Unreal was supposed to have a Sega Dreamcast port, but it was never released. I've read that someone got the Unreal Tournament Engine to run Unreal on Windows with a patch a few years ago. I wonder, is anyone interested in hacking at Unreal Tournament Dreamcast to make it play Unreal? I tried modifying some things awhile ago, and while it looks like it is an actual Unreal engine ported to Dreamcast, it is too different from the Windows version for me to figure out.