Doom Wiki

"Energy based weapon developed in the Mars weapon facility. Unit is powered by plasma canisters manufactured in the EnPro facility."
PDA Description [src]

The Plasma Gun in Doom 3 is an energy-based weapon first found in a hidden location in Sector 3 of the Alpha Labs. It is slightly different from its earlier counterpart, as the weapon model is based off of a futuristic assault rifle with a bullpup design (the weapon ammo is reloaded and ejected on the back of the weapon). The weapon fires blue plasma bursts which originates from the cells stored inside the back of the weapon.

A blueprint of the Plasma Gun.

Similar to the Chaingun, BFG 9000 and newcomer Machine Gun, the Plasma Gun discards the game ammo HUD because it has its own ammunition counter in a small monitor located at the rear upper end of the weapon itself. Ammunition comes in the form of Plasma Cells, which appear to be bulky bottles that glow a luminescent blue and possess a blue-colored tip. Individual Plasma Cells hold 25 units of projectile, whereas a box of 2 Cells holds double the amount. Ammunition for this weapon are generally easier to locate throughout the entire game relative to Rockets, Ammo Belts, and BFG Cells, and are particularly abundant in the EnPro facility.

Tactical Use

The Plasma Gun before being picked up

The Plasma Gun is a very powerful medium to long range weapon; making it comparable to the higher-end weapons such as the Chaingun and the Rocket Launcher. It has a high firepower, a good rate of fire, and superb accuracy. Even stronger enemies like the Mancubi, Revenant, and the Hell Knight can instantly be incinerated by the plasma bursts in a matter of seconds, provided if the shots all connect. The Plasma Gun is also effective at destroying enemy projectiles as each shots create a "flak zone" to eliminate the Revenant's and Mancubi projectiles in-flight.

The weapon's primary weakness is the slow speed of the projectiles, traveling slower than the shots fired by both the Chaingun and the Machine Gun. The slow speed of the plasma projectiles means that flying monsters, such as Cacodemons and Lost Souls can most likely avoid the plasma shots by moving to the side, before it hits them. This can be problematic if you were to fight against a swarm of Lost Souls at a close distance, as these monsters can attack very quick and sudden. Make sure you can connect your shots accordingly when facing these enemies. Alternatively, it is best to use Machine Gun or Chaingun due to the weapon's quicker projectiles.

Video Disk - Series 3 Plasma Gun Briefing

This video disk can be picked up in the Combat Prep room in Mars City.

Note: The video disk cannot be picked up after returning from the old comm facility.

Creator: UAC Advanced Weapons
Date: 07/28/44
Informational Video on the Series 3 Plasma Gun
Representing yet another great accomplishment of the UAC, the Series 3 Plasma Gun is an extremely versatile, medium range combat weapon. Harnessing the exhaustive resources of synthetic plasma, the plasma gun meets the critical requirement of low cost, abundant ammunition for today's highly mobile military.
Capable of sustained firepower due to the latest advancements in plasma injector technology, this weapon's light weight and high yield make it desirable for most combat scenarios.
Always on the forefront of technology, the UAC is making safer worlds through superior firepower.


  • The Plasma Gun no longer uses the same ammunition as the BFG 9000.
  • Strangely, the Plasma shots can sometimes cause enemies to be thrown off at great distance, as if they're lightweight. This also applies to heavier foes like the Hell Knight or the Mancubus. No other weapons share this trait, as upon death, enemies will either collapse or get thrown off at a short distance from splash damage.
  • The Plasma Gun is a very wanted weapon around Mars City, given a mention of it in a citizen's email and on a video disk found in a weapons storage room at Mars City. It can also be found in an armory at Marine Headquarters in the same level, and the first bit of the cells is also found in Mars City Underground, hidden in a utility locker along with a Health Dispenser.
  • Theresa Chasar is credited for researching the Plasma Gun.
  • The two Plasma Guns available in the final level, Primary Excavation, are multiplayer models. This does not affect their behavior though, because the game is flagged as single player; but it does give the player 30 ammo on pickup instead of the regular 50.