Type in the following code during gameplay:
FWBARNEY-Frame rate counter
FWBERT-Jetpack - press F to turn on/off, Z to fly
FWIGIVEUP-Skip mission
FWMARIT-Full health and oxygen
FWMIGA-Full weapons and ammo
FWMITHRA-Invincibility
FWKITTY-Invisibility
FWWARP-Warp to mission - type FWWARP## from 00 to 17
P & S-Press simultaneously to capture a screen shot in 16-bit TGA
format