Duke Nukem 64

Cheat menu: press left,down,l,l,up,right,left,up.
all items: press r,c right,down,l,c up,left,c right,left.
invincibility: press r,c right,r,l,r,r,r,left.
no mosters: l,c up,left,l,c down,right,left,right.
level select: press r,r,r,c down,right,up,left,c up