Almost 12 years ago Duke Nukem 3D was a fun and different game compared what else was out there at the time.
12+ for a sequel ? That's not even funny, it's criminal.
Nasa have designed, built and deployed 2 Mars Rovers in less time.
id Software have release/co-produced:
Quake II (1997)
Quake III Arena (1999)
Expansion: Team Arena (2000)
Doom 3 (2004)
Doom 3: Resurrection of Evil (2005)
Quake 4 (2006)
Enemy Territory: Quake Wars (2007)
+ a lots of details and a trailer for Rage
Not to mention John Carmack, in his spare time, also knocked up a couple of game engines for cell phones and helped launch a company to produce games with them AND with Armadillo Aerospace ALMOST won the X price ( twice! )
12 Years is a long time in gaming.
If DNF was entirly CG it wouldn't have taken so long !
What else has taken less time to make ? oh yes
the Lord of the Rings Trilogy, and who would bet against this:
I bet if and when DNF is released, you could play and complete it in less time than it would take to watch the complete LotR extended editions and ultimately the majority of people will feel they enjoyed the movies more than DNF.