Do different difficulties and you must be a freakin prodigy haha, I guess I started it at medium so thats why it might have taken longer
Well since when was the "X hours of gameplay" true in a game description? Of course it has to be exaggerated a little bit to attract players, or based on slowest possible playthrough. I don't think developers are humble enough to set a timer and tell players exactly how long the game is.
Oh! You know what, it completely slipped my mind. I beat single player in 2 hours, on Hard difficulty. I'm proof it happened.
Oh I forgot, I beat Hard in 15 minutes, and I unlocked all the secret weapons and I drove a hydroplane on the snow level then reached the top of the leader board in 2.5 minutes while posting sarcastic comments on touch arcade! I am all that is man.