Press T during game play, then type /debug on. Then, press CTRL + ALT + 7. The message "Game mode off" will appear to confirm correct code entry. Then, enter one of the following codes to activate the corresponding debug function.
CHEAT FUNCTION - CHEAT CODE Extra ammunition - CTRL + ALT + 5 All weapons - CTRL + ALT + 6 Ignored by enemies - CTRL + ALT + 3