I have to add my own disbelief in "da_frog" on this thing.
Split screen? Come on.
Are there any established programmers here who get anything but the feeling this guy is trying to put one over on everybody? It just "feels" bogus and much of what he's said is just plain off the deep end. This is the same guy that's promising about a dozen other apps, too, right? Kind of like the other guy who solicited a ton of ideas from people then promptly disappeared.
I really don't understand why people do this. Porting is not a simple task, and in many ways, requires MORE skill than that required to write an app for a given platform.
I have the HL2 source here, but I've not dug into it. Considering there was supposed to be parallel development for the Xbox, it's possible the build tree migth include some of the code already, but as the port is surely being handled by a different developer, probably not, so the port will require quite a bit of effort. I'd be amazed if the experienced, established Xbox "underground" developers have gotten it up and running yet on the Xbox, let alone make any changes to the engine - though I don't doubt they've played with it.