Backpack



The backpack is a powerup that doubles the player's ammo-carrying capacity. After picking up a backpack, the player is able to carry up to 400 bullets, 100 shotgun shells, 100 rockets, and 600 plasma cells at once. The backpack also gives 10 bullets, 4 shotgun shells, 1 rocket, and 20 cells when picked up (20, 8, 2, and 40 on I'm Too Young To Die and Nightmare!), which basically equal to picking a small ammo of every respective weapon.

If the player picks up a subsequent backpack, he only receives the extra ammunition. A backpack can still be picked up even when the player cannot carry any more ammo of any type.

In some Doom versions having a backpack also doubles the amount gained from picking up ammo.

The backpack's effect lasts until the end of the episode in Doom and until the end of the game in Doom II/Final Doom.

Using the cheat code idkfa or idfa to give the player all weapons and maximum ammunition does not give the player a backpack in vanilla Doom. The backpack is the only powerup which does not have a corresponding idbehold cheat code.

Backpacks are not included in the items percentage displayed at the end of each level.

Appearance statistics
The IWADs contain the following numbers of backpacks: