Cheatcodes:
Type in these codes in the console brought forth by the tilde key (~):
iwillsurvive -- God-Mode.
raindropskeepfallinonmyhead -- More ammo.
takeittothelimit -- Ammo reload.
hitmewithyourbestshot -- Computer rocks.
closetoyou -- You become invisible.
letmego -- Now you can jump levels.
sky -- Removes the clouds, and makes the game a little faster.