Here is a list of cheat codes for Duke Nukem 3-D. All you have to do is type them in while you are playing. They do not have to be in caps.
type this - this happens
DNCORNHOLIO - GOD MODE
DNKROZ - GOD MODE
DNVIEW - same as F7
DNHYPER - STEROIDS
DNITEMS - ALL ITEMS
DNWEAPONS - ALL WEAPONS & AMMO
DNKEYS - ALL KEYS
DNSTUFF - EVERYTHING
DNSCOTTYxyz - substitute x,y,&z with the episode& level #s and you will go there
DNSKILLx - substitute x with 0-3 and your skill level will change
DNUNLOCK - UNLOCKS ALL DOORS
DNMONSTERS - TURN OFF OR ON THE MONSTERS
DNCLIP - WALK THRU WALLS
DNSHOWMAP - SHOWS WHOLE MAP
DNCASHMAN - MONEY FLIES OUT WHEN YOU PUSH THE SPACE BAR
DNCOORDS - HARD TO EXPLAIN
DNDEBUG - SHOWS SOME DEBUG INFO
DNBETA - SAYS "PIRATES SUCK"
DNALLEN - SAYS "BUY MAJOR STRYKER"
DNTODD - SAYS"REGISTER COSMO TODAY"