Wired has a really good article from last year about why DNF was never finished: <a href="http://www.wired.com/magazine/2009/12/fail_duke_nukem/" rel="nofollow">http://www.wired.com/magazine/2009/12/fail_duke_nukem/</a><p>Executive summary: The first game was <i>too</i> successful. Failure can be, and often is, a good thing.<p>"<i>Normally, game developers don’t have much cash. Like rock bands seeking a label to help pay for the cost of recording an album, game developers usually find a publisher to give them an advance in exchange for a big slice of the profits. But Broussard and Miller didn’t need to do this. 3D Realms was flush with cash. [...] Yet the truth is, Broussard’s financial freedom had cut him off from all discipline. He could delay making the tough calls, seemingly forever. One day, Broussard came in and said, ‘We could go another five years without shipping a game’ because 3D Realms still had so much money in the bank</i>"