Before using any of these cheats you have to press the ~ button in the upper right hand corner of your keyboard

GOD .................................. God Mode
NOTARGET .............................. Nothing sees you untill you shoot.
KILL..................................... Suicide.
FLY .......................................Fly mode.
NOCLIP ................................ Power to walk through wall.
IMPULSE 9 ............................. Full weapons and ammo.
IMPULSE 255 .................................. Instant Quad.
IMPULSE -1 ................................ Everything but the weapons.
IMPULSE 11 .......................................Jewels.
GIVE # .................................... Gun number.
GIVE C # ..................................... Charge (# of charge wanted.)
GIVE N # .............................. Nails (# of nails wanted)
GIVE R # ................................Rockets (# of rockets wanted).
SV_GRAVITY .................................... Change Gravity.
GIVE HEALTH # .................................. Health (# up to 999).
MAP E#M# ...................................... Level warp.