Hit ALT and  at the same time to be able to enter these codes:
 
 GARBLE          Garble cheat codes toggle
 SUPERUZI        Get the Super UZI
 ICANTSEE        Show viewscreen
 WHOAMI          Shows your name
 COUNTERS        Shows current co-ordinates
 VERSION         Shows version
 HELLO           Shows message: Hello?
 WILLNOTSTOP     Invincibility
 ARNOLD          All weapons
 SLUGS           All ammo
 SURGERY         Full health
 SUPERUZI        Get the Super UZI
 TARGET          Enables targeting box on enemies
 ILLBEBACK       Skips to next scene
 NITROUS         Speeds up game