Note: The following codes require an Xbox 360 controller to be activated. Unlock the following challenge rooms at the "Challenge Room" menu by entering the corresponding sequences of buttons at the "Press Start" screen:

CHALLENGE ROOM - CHEAT CODE
Arron Sedillo challenge room - RIGHT, DOWN, LEFT, UP, LB, RB, Y(2), A(2), START.
EuroGamer challenge room - DOWN, UP, DOWN, UP, LEFT, LB, X, LB, X, Y, START.
GamesRadar challenge room - RB, Y, X(2), UP, DOWN, LB(2), UP, DOWN, START.
IGN challenge room - UP, DOWN, Y, X(2), Y, DOWN, UP, LB(2), START.
Major Nelson challenge room - LB, X(3), RIGHT, DOWN, LB, LEFT, Y, DOWN, START.

To unlock Super Hard difficulty, complete the game.