To further explain what went wrong, DNF went through SEVERAL engine changes, from Quake 1 to Quake 2, to finally Unreal. Then, George Brossard looked at all the shit being done at the time and figured "Duke should have that too!".
Only problem was, George would have the actual devs at 3D Realms pretty much disrupt their work for some feature like dynamic lights and stuff. The 2001 build was THIS close to completion, but then George wanted a unique lighting system that totally FUCKED the game. The devs had to redo all the models, maps and everything in between just to make the game run properly. THEN Unreal 2 came out, and...