ahh, ahh!, AHH!, AHH!!,AHHH!!!!!
Ha ha ha! It is true! I found it hard to believe that the source of Duke Nukem 3D was never released. To whom ever ports this *winks to Dan*, I shall also be in their debt forever.
Also, Duke Nukem II would be suitable for PPC, it's a side view game, I had it way back in the day, excellent arcade style game. As for other FPSs, Blake Stone: Aliens of Gold was Apogee's project after Wolfenstein 3D came out. I would guess that the code is similar to Wolfenstein, but I have no idea, or any idea if the source is out. Also, remember the game Corridor 7? Back in March of 1994? I thought it was good way back then, but I just searched for it on the Internet, and everyone gave it horrible reviews. I remember it being really scary, but I was 7 years old back then. If the source is released, I recommend Corridor 7.