Once the game has starrted to load, press start to pause the game. Now enter the following combination: Top C, Bottom C, Left C, Right C. You'll see Cheat appear at the bottom of the menu. Select the Cheat Menu now. The following codes must be entered rather quickly inside the cheat menu. You'll hear a "swoosh" if done correctly, otherwise a "hmmmm" if not.
God Mode- Left C, Right C, Bottom C.
Level Select- Left C, Left C, Right C, Right C, Bottom C, Top C.
Butcher- Bottom C, Top C, Left C, Left C.
Health- Left C, Top C, Bottom C, Bottom C.
Clipping- Top C (20 times), Bottom C.
These codes can be input anywhere, but you have to go to the Collect Sub-menu to use them.
All Keys- Bottom C, Top C, Left C, Right C.
All Artifacts- Top C, Right C, Bottom C, Top C.
All Weapons- Right C, Top C, Bottom C, Bottom C.
All Puzzle Items- Top C,
Bottom C, Left C, Right C.