PC | Submitted by GamesRadarHacks
*Edit the hardline.cfg file in your hardline directory. Add the following line as shown to the end of the file (as the last line) to enable the cheat keys:
CHEATING IS SOMETIMES USEFUL BUT FOR HOW LONG ???
Once enabled, cheat at will:
BACKSPACE: hit this key to kill all enemies on the current screen.
HOME: hit this key to add main weapon ammo.
INSERT: hit this key to restore full health.
PAGE UP: hit this key to add accessory weapon ammo.
X: hit this key to toggle invincibility.