Beating various levels will unlock 9 extra costumes:
1: Original Superman
2: Golden Age Superman
3: Silver Age Superman (Red)
4: Silver Age Superman (Blue)
5: The Return of Superman (Black)
6: 90's Superman
7: Kryptonian Superman
8: Post "Our Worlds at War' Superman in mourning
9: Kingdom Come Superman
Free roam option
Successfully complete mission 4 to unlock the free roam option. This allows you to replay any mission that has been completed in single mission mode.
Freeze graphics
Pause game play, then quickly press R, L, Black, White, L, Y(2), Black, R, White. The sound of an explosion will confirm correct code entry.
Put Out Building Fires Faster
Hold down the Freeze Breath button for a couple of seconds to charge, before you let go and you will put out the fire in one breath. Also the lock brackets are visible through buildings and other objects so you can easily tell if there is fire on the other side of a building.
Unlimited Life
To get unlimited life press pause and then press Black, White, L, X, L, White and you should hear an explosion if you entered the cheat correctly.
Unlock Everything
Pause the game and press R, Black, Y, Black, L and White to unlock everything.
X-Ray graphics
Pause game play, then quickly press L(2), R, L, Y, X, White, Black(2), White. The sound of an explosion will confirm correct code entry.
Extra Costumes...