MDK 2

Toggle slow-motion 
While playing as Max, hold [Fire] and press [Equip Up] four times.
If you entered the code correctly, a message will appear.

Cheat Codes 
While playing a game, press ~, then type one of the following codes at the "Omen" prompt to activate the corresponding cheat function:

RESULT          - CHEAT CODE  
God mode        - mdkGobSetDamageFilter(mdkGetPlayerGob(),0) 
Toggle God mode - GodDebugToggle() 
Nude Kurt       - KurtGetNaked() 
Level 1         - mdkNewGame(1,12) 
Level 2         - mdkNewGame(2,12) 
Level 3         - mdkNewGame(3,12) 
Level 4         - mdkNewGame(4,12) 
Level 5         - mdkNewGame(5,11) 
Level 6         - mdkNewGame(6,8) 
Level 7         - mdkNewGame(7,11) 
Level 8         - mdkNewGame(8,8) 
Level 9         - mdkNewGame(9,13) 
Level 10        - mdkNewGame(10,7) 
Level 10/1bonus - mdkNewGame(11,1) 
Level 10/2bonus - mdkNewGame(12,1)