Any marketing plan for the game needs to take into account the enormous amount of gamer goodwill the title has built up and lost over the years. The game was so often delayed that its release date became a punchline similar to "when hell freezes over" -- so dealing with the fans delicately is a must.
Now, while the development of "Duke Nukem Forever" languished, the fans of the franchise didn't sit idle. One fan in particular, Frederik Schreiber, has undertaken to remake the entirety of "Duke Nukem 3D," the 1996 classic predecessor of "Duke Nukem Forever," with an updated graphics engine, calling the new project "Duke Nukem Next Gen." Generally, these sorts of projects are completely underground, or else they end badly, with the developer and rights holder sending a cease and desist letter. But in this case, Duke Nukem's current developer, Gearbox, decided to take a different route -- they granted Schreiber and his dev team a noncommercial license to develop their own version of the game.
This was a smart move on the part of Gearbox, because cultivating a community that's dedicated to the "Duke Nukem" brand was exactly what they needed to do to publish a successful game next year. "Duke Nukem Forever"'s long and arduous development and hype cycle has meant that there are a lot of gamers out there who are simply tired of hearing about the game, or worse, believe that no matter how good the game is, it just won't live up to the hype.
I've no doubt that detractors at Gearbox argued that they'd be creating a free competitor product to "Duke Nukem Forever" by failing to quash this ambitious fan project, which would ultimately cannibalize their own audience. And, let's face it -- if "Duke Nukem Forever" turns out to be derivative or disappointing, and fails to live up to its high expectations, that's probably true. We can read into Gearbox's decision to let the community project go forward that they have a great deal of confidence that, despite the presence of a free, competitive product, people will still want to purchase their game -- and that's exactly the image they needed to project.