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 energy cell units at once. When picked up, the backpack also gives the equivalent of the small ammo item for each type of ammunition: 10 bullets, 4 shotgun shells, a rocket, and 20 energy cell units (or 20, 8, 2, and 40 on the "I'm Too Young To Die" and "Nightmare!" skill levels).

If the player picks up a subsequent backpack, the only benefit is any extra ammunition that is received. A backpack can be picked up even when the player cannot carry any more ammo of any type.

The backpack's effect lasts until the end of the episode in Doom and until the end of the game in Doom II. However, if the player dies, the effect will be nullified.

Using the cheat code idkfa or idfa to give the player all weapons and maximum ammunition does not give the player a backpack. 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 per skill level: