It's taken longer to develop than the mapping of the human genome. It's the first Google result for "When it's done." It's birthed the longest running development period in video game history, and the longest running joke in internet history. It's still not out.
Maybe the one thing you can't say about Duke Nukem Forever is that it's been canceled. And now, thanks to that fortune, we may yet be treated to a release of the infamous game. But how did we get here?