Supplies (Doom 3)

Health
Unlike in previous games, in singleplayer mode the player's health cannot go above 100.

Med kits
The med kits come in two variations: a small med kit which replenishes 15 health, and a large one that replenishes 25 health.

Health stations
The player can also replenish health from health stations found on the levels. The health stations have variable amounts of health in reserve (the maximum in the original levels is 100), and it gives the player 10 health per one use until the player's health is full or it runs out of health in reserve.

Armor
The armor in Doom 3 absorbs 30% of the damage the player takes in singleplayer mode, and 60% in multiplayer mode. The maximum amount of armor the player can have is 125 in singleplayer, and 200 in multiplayer, but in multiplayer the armor drops by 2 every 1.5 seconds when it's above 100. The armor pickups in Doom 3 come in two varieties: armor shards that give the player 5 armor points and security armor which gives the player 50 armor points.

Air canisters
When the player has to run across the surface of Mars or other area that has no breathable air in it, the player has a very limited supply of air available. If the player runs out of air they will start taking 10 damage every three seconds. To replenish air the player has to look for the air canisters scattered around the area. An air canister replenishes 50% of the player's air meter upon picking it up.

Enviro tanks
The enviro tanks appear only in the original version of Doom 3: Resurrection of Evil. In Erebus - Level 5 at one point the player has to proceed through waste tunnels using the enviro suit to shield themself from the toxic gasses. During this sequence, the "Enviro" count appears and it decreases by one about every second and when it ends the player starts receiving damage from the environment. To replenish the bar, the player has to collect the enviro tanks, most of which are obtained by killing bio-suit zombies roaming around the area. Each enviro tank replenishes 30 points of the enviro count. In the BFG Edition of the game, the waste tunnels no longer require wearing the enviro suit, so the enviro tanks are completely removed from the game.