All Codes must be performed during the [era:ks] screen. A voice clip will play if you entered the code correctly.

Easy Mode:
Up, Up, Down, Down, Left, Right, Left, Right, Attack, Jump

Pamela Mode:
Up, Down, Next weapon, Previous Weapon

Sterbich Mode / 1-HP Mode:
Previous Weapon, Previous Weapon. Previous Weapon, Next Weapon

Harder Stages:
Left, Left, Left, Right

Debug Mode:
Up, Down, Attack, Jump

Not a cheat code, but if you are having issues with Pamela constantly dashing into bottomless pits, you can disable command dash by pressing 1 on your keyboard during game play.