Hexen 64

While playing, pause the game and press C-Up, C-Down, C-Left, C-Right. A CHEAT option will appear on screen. Enter this menu, then quickly enter one of the codes below.
God Mode -- C-Left, C-Right, C-Down
Full Health -- C-Left, C-Up, C-Down, C-Down
Level Select -- C-Left, C-Left, C-Right, C-Right, C-Down, C-Up
Butcher -- C-Down, C-Up, C-Left, C-Left
No Clipping -- C-Up 20 times, C-Down
Collect Mode Cheats
Enter these codes on the Collect Mode screen. See your manual for details.

All Artifacts -- C-Up, C-Right, C-Down, C-Up
All Keys -- C-Down, C-Up, C-Left, C-Right
All Puzzle Items -- C-Up, C-Left, C-Left, C-Left, C-Right, C-Down, C-Down
All Weapons -- C-Right, C-Up, C-Down, C-Down
Skip Part of the Hub
At the core of the seven-portal hub there are three stairs that must be raised. After you raise the first flight of stairs, walk halfway up them. You will see the other two platforms that the other two staircases lead to. If you try hard enough, you can actually jump to the smaller ledge, skipping a part of the hub!

This cheat works on All difficulties, including the Toughest difficulty. It will only work with inventory items only. To do it, pick up an item, then quickly open up the Hexen 64 Game Menu, Temporarily save the game, then reload it. Whalla! You will have two of the same item. You must time it right to get the same item twice. It can be repeated more than once until you need as much as you want.