The third part of Duke Nukem: History of a Legend is out now, detailing the dark days of Duke Nukem Forever
's development--the seemingly endless crawl up to 3D Realm's closure in 2009. The developers are all pretty honest in this one although they stop short of pointing the finger at any one person in particular. The problems seems to be the same one everybody predicted: no structure, no milestones, just constant iteration with no end in sight.
This explains why parts of the finished game feel relatively new while other sections are positively ancient. It's too bad too, because a lot of the cooler, more cinematic ideas from the 2001 and even 1997 trailers were scrapped in favor of ripping off every big shooter that came out. I'd much rather have pitched shootouts on the highways of Vegas than Half Life 2 physics puzzles that I was already tired of in Half Life 2.
What amazes me most is David Riegel, founder of Triptych games, spent five and a half years
of his life on Duke Forever. Most Zelda games don't even spend that long in development, but that time was just the last stretch of DNF's vicious development cycle.