1. Duke Nukem Forever
Development Begun: 1997
What did you expect? Duke Nukem Forever is the biggest (and longest) running joke in the history of the gaming industry, and with good reason.
Though it's not unusual for a delayed game to stagnate for a while without a definite release date, DNF went for ten years without one. When 3D Realms was downsized in 2009 and the DNF team was disbanded, most gamers lost all hope of ever seeing the game. Sadly, that probably would have been for the best.
The game that 2K ultimately decided to produce was, at the same time, both everything fans wanted, and a total train wreck. The problem wasn't so much the game itself as that the industry has simply grown up.
Duke's bawdy sense of humor, racism and sexism, and general lack of sensitivity toward everything simply doesn't appeal anymore like it did a decade ago. That's what happens when a game takes almost 15 years to develop. Let's hope nothing like this ever happens again, because it discredits our entire industry. Rant over.