Well as the others said.. he rushed through the levels...
Reviewers from NeoGAF said this: "I won’t spoil anything, but anyone who has played 3D Land, knows that finishing the game is really not finishing it at all. That’s all I can say.
It’s a lot longer than 8 hours, folks. I can’t really say much more than that, but don’t worry."
Seems like there are going to be the special-worlds again ;)