Just like Doom 64 and Turok, Hexen contains some really good cheat codes. The first thing you must do is start a game. You can pick any play mode (normal, co-op or deathmatch) and can have any number of players. You can also resume a saved game. Once the game is started or loaded, press start to pause the game. Now press the following button combination: Top C, Bottom C, Left C, Right C. If done correctly, you'll see Cheat appear at the bottom of the menu. Go into the Cheat Menu.
The following codes must be done rather quickly inside the Cheat Menu. If you pause for even a second, the codes will not work. The codes listed underneath the Collect Sub-Menu can be entered anywhere, but you have to go to the Collect Sub-Menu to use them. If you input the code correctly, you'll hear a swooshing sound. If the code is invalid, you'll hear a Hmmm... sound.
Left C, Right C, Bottom C
God Mode (invincibility)
Top C (20 times), Bottom C
Clipping (walk through walls)
Left C, Left C, Right C, Right C, Bottom C, Top C
Visit (level select)
Bottom C, Top C, Left C, Left C
Butcher (kills all enemies currently on-screen)
Left C, Top C, Bottom C, Bottom C
Health (gives you full health)
Bottom C, Top C, Left C, Right C
Top C, Right C, Bottom C, Top C
Right C, Top C, Bottom C, Bottom C
Top C, Left C (three times), Right C, Bottom C (twice)