Invincible, Next level
During the game press left shift and f11 at the same time. You will now get a cheat menu. Type HOLLOW MAN (enter) to be invincible. Hit enter to get back to the game.
To win the level and get to the next level, you go to the cheat menu (left shift and F11) and you type CLINT (enter). To get back to the game hit enter.
Cheat Codes
To enter the cheat mode you have to press LEFT SHIFT + F11 then you can enter the next cheats:
Cheat Code - Effect
timeless - Stop Time
schneider - End Current Level
clint - Win Current Level
jackal - Ammunition
hollow man - Invisibility
show me all - Show All Objects
zeus - Help From the Gods
fidel castro - View Dialogs
medic - View Hints
powerman - New Weapon
epitaph - Toggle Victory Condition Display
whats my destiny - Toggle Display Short Briefings