All of these cheat codes can be activated in the Extra's menu. Have fun. Seeyou at Cheating Dome!

Unlockable	How to unlock
Big Head Mode in Extra Game Setting	Use early preorder download code.
Concept Arts	Complete the game once in any difficulty.
Developemt Timeline	Complete the game once in any difficulty.
Duke 3D Freeze Ray	Complete the game.
Duke Sound Board	Complete the game once in any difficulty.
Grayscale Mode	Complete the game.
Head Scale	Complete the game.
Infinite Ammo	Complete the game.
Instagib	Complete the game.
Invincibility	Complete the game.
Mirror Mode	Complete the game.
Movies	Complete the game once in any difficulty.
Screenshots	Complete the game once in any difficulty.
Triptuch	Complete the game once in any difficulty.