If you wanted to read a lesson on what not to do with a project, I suggest you go over to Wired.com and read “Learn to Let Go: How Success Killed Duke Nukem“.
Duke Nukem 3D was a smash hit. So in hindsight, I can see why George Broussard and 3D Realms thought they could go for a repeat performance. They had the funds and the talent, but so do many others out there. But they didn’t factor in the fact that all the stars and planets aligned for Duke Nukem 3D, so to recapture that exact moment requires a monumental effort — especially from a tech perspective.
Chasing technology from not one, but two technological powerhouses (Epic and id) was not the smartest move. And for what? Somewhere along the way, 3D Realms forgot what made Duke Nukem 3D awesome. It wasn’t the tech, it was the interactivity and personality; that’s what people remember when they think of Duke. But somehow they forgot that.
Too much money, independence and passion was associated with Duke Nukem: Forever; a victim of its own success.