It's been seen being played and is reported to be "looking great".

Duke Nukem Forever screenshot

The existence of Duke Nukem Forever has been confirmed by Shacknews, having seen the game being played for around half an hour.

"I have seen it. Maarten has seen it. We watched actual interactive gameplay being interacted with," said Shacknews' Steve Gibson.

"For a good half hour Shacknews witnessed several different DNF gameplay scenarios, mechanics, and environments being demonstrated.

"We actually got to see the truth of Duke curator George Broussard's many past claims, including environmental puzzles and interactivity, a host of finished weapons, the existence of an in-game forklift, and plenty of heads and arms being blown off."

And after their time seeing the game, the Shacknews guys agree that "Duke Nukem Forever is looking great", which is good to hear.