BFG9000/Doom 3

"This prototype fires a threaded variable energy charge. UAC technicians have warned of stability issues at full power."

- PDA Description

The BFG 9000 (initials for "Bio Force Gun" or "Big Fucking Gun") of Doom 3 is one of the weapons created by the Union Aerospace Corporation under its weapon research program, and is considered the most powerful weapon of the game, capable of causing damage to a single enemy for more than 1700 hit points. It is first introduced in UAC Administration, when Campbell opens his suitcase to an unknown green glow (green being associated with the colour of the BFG projectile). It is seen being used in Alpha Labs Sector 4 and Communications by Campbell, however the player only manages to get their hands on it in Sector 2a of the Delta Labs. It is lost during the transit to Hell (where it is available as a pick-up, only to lose it again during the transit back to Delta), but the player manages to retrieve it in the CPU Complex from Sabaoth, who had killed Campbell and taken it from him.

Weapon schematics
The BFG in Doom 3 mostly functions in a different way from its Doom counterpart, as the projectile exists in the form of a computer chip contained within a ball of relatively slow-moving green plasma. The newer version also follows a charge-based system; holding down the trigger causes the weapon to charge up for a more powerful shot (up to 4 levels of charge), the status of the charge being displayed on a small monitor (which also displays the ammo count and dispenses the game HUD, just like newcomer Machine Gun, the Chaingun and Plasma Gun). The chip identifies and shoots rays at opponents that will debilitate them prior to the explosion of the plasma projectile. The damage of these rays is 200 (over 10 points per second). The effects of the weapon are devastating; a single-charged projectile can obliterate any weaker monster, whereas a fully-charged shot will kill any monster up to a Vagary. "Elite" monsters with a lot of hit points such as the Hell Knight or the Mancubus generally require a double or triple-charged shot to kill, and this weapon is ideal for taking out Arch-Viles quickly, when the Soul Cube is not available.

Unlike in the classic Doom and Doom II, the BFG 9000 in Doom 3 no longer uses the same ammo as the Plasma gun, but its own type of cell instead. The BFG Cell exists as a green cylinder with an actively vibrating sphere inside (similar to an atom), and holds 4 charges. Unlike in Doom II, BFG cells are very hard to come by and are placed in relatively obscure locations, and it is therefore recommended to use the weapon sparingly. Based on Michael Abrams' report, this BFG is lighter than "previous prototype models" (hinting an older version or a predecessor). The weight saving may be credited to reducing the projectile energy capacitor or containment field. This noticeably reduces weight but also makes the user more vulnerable as excess energy may detonate should the containment fail. The ammo is reloaded from a magazine compartment located on the left side of the weapon. The green plasma orb serving as the weapon's power source may be related to the green glowing chemical dump of the energy production (fusion process in this storyline produce steam and green sludge) process utilized on Mars. This is starkly different from the energy canisters used on the Plasma Gun, which store a glowing bright blue mass of energy, which is presumably a main product of the energy facility (EnPro), explaining the abundant supply of plasma energy bottles in the EnPro facility. The BFG ammunition itself requires specialized chips to control detonation, preventing mass production of the BFG cell. It is possible that the Mars facility was planned to be designated as the BFG's ammunition production plant (one of the reasons why Swann was authorized to have a "hard hand" policy on Betruger).

Tactical analysis
The weapon is recommended for medium to long-range combat, as firing at a monster up close will severely damage the player due to the weapon's blast radius. Moreover, the longer the projectile exists undetonated, the longer the time it will have to attack other enemies within the vicinity with its rays. The BFG is also recommended for usage in areas with heavy enemy presence due to its targeting system, as the other weapons specialize more in single-enemy combat. It is also advisable to deploy the weapon during boss fights, such as in Caverns 2, due to the heavy premium on the ammunition. Do not overcharge the weapon, as it can overheat and explode, killing the player instantly.