Red Faction

Equip the grenade launcher and when an enemy charges at you, either fire a rocket at the ceiling above your foe or just in front of his feet. This should be a 1 hit kill; or aim the shotgun at your opponent's leg, this is a 2 or 3 shot kill.

Full Health:

During gameplay, press Select, Up, Left, Down, Right, Up, Up, Down, Down, Circle, Circle.

All Weapons:

During gameplay, press Select, Down, Down, Left, Right, Left, Right, Up, Up, Square, Square.