The main 'heath' item that is to be collected in Deadside. When Shadow Man destroys an enemy or pot with his ShadowGun a white lifeforce energy will be left behind, if not collected quickly it will disappear. The Lifeforce Meter shown in the corner of the screen shows how much lifeforce energy the player has on the outermost part of the ring (the red areas). One lifeforce is worth one section on the Lifeforce Meter. Although lifeforce energy is indeed 'health' if it reaches zero Shadow Man does not die but just re-spawns from his last teddy bear save point or entry/ exit of the level.
In Liveside while playing as Mike the same area of the Lifeforce Meter will be changed slightly to show how many health kits the player has acquired instead of lifeforce energy.