In the full version there are:

 \RAGAMUFFIN     Invincibility
 \ARMS           Full weapons and ammo
 \DIG            Walk through walls
 \GIFT           All items
 \FMK            Full health
 \OVERDRIVE      Microchip powerup
 \BLOAD          Level warp
 \VICI           End level
 \SPUTNIK        Full automap
 \AMOBJECT       Shows objects on automap
 \AIMOVE         Enemy AI toggle
 \GOBBET         Gib Yourself
 \FRAME          Display framerate

 Some from David Walker, plank@eskimo.com

 But:
 If you can make it through the entire game without cheating you will
 get a bonus level and bonus character to try.

 In the demo there are the following codes:

 \FUSHIPI        Invincibility toggle
 \GUNS           All weapons and ammo
 \BLOODLUST      Powerup weapons
 \TUNNEL         Walk through walls
 \AMOBJECT       I think this is some sort of map of the whole area.

 From Dan Ritter, dritter@lynx.bc.ca