Doom 3

=== Setting ===
Doom 3 is set on the planet Mars in the year 2145. According to the game's backstory, the Union Aerospace Corporation (UAC) has grown to become the largest corporate entity in existence with near-unlimited funds and has set up a research facility on Mars. At this base, the UAC are able to conduct research into several scientific areas, including advanced weapons development, biological research, space exploration and teleportation, outside of legal and moral boundaries. As the player progresses through the game, they learn that the employees on the base are unsettled due to a large number of incidents involving hearing voices, unexplained sightings and increasing cases of paranoia and insanity, often leading to fatal accidents with the facility's machinery. Rumors regarding the nature of experiments in the UAC's Delta Labs division are especially prevalent among the base's employees.
Much of Doom 3's story and dialogue were written by author Matthew J. Costello.



Characters

There are five main characters in Doom 3. The player assumes the role of an anonymous Space Marine corporal who has just arrived on the UAC's Mars base. The player's non-commissioned officer in-charge is Master Sergeant Thomas Kelly (voiced by Neil Ross) who gives the player objectives and advice over the player's radio for the first half of the game. The antagonist in the story is Dr. Malcolm Betruger (Philip L. Clarke), the head scientist of the UAC's enigmatic Delta Labs division, who is revealed to be working in collaboration with the forces of Hell to cause the subjugation of humanity, and his demonic voice frequently taunts the player as the game progresses. The final two principal characters are Elliott Swann (Charles Dennis), a representative of the UAC's board of directors, and Jack Campbell (Andy Chanley), a space marine who acts as Swann's enforcer and is armed with a BFG 9000. Swann is sent to Mars to check up on Betruger's research and investigate the rising number of accidents on the base after a request for assistance from a whistleblower. Swann is almost always accompanied by Campbell, and the two are often shown in the game to be a few steps ahead of the player but cannot be reached and directly communicated with until late in the game. The game also incorporates a large host of minor characters who add details to the story or assist the player in certain segments. The player encounters multiple scientists involved in the various research and development programs and archaeological digs through the UAC base, as well as fellow marines and security guards. Civilian employees engaged in bureaucratic work and maintenance workers are also seen.



Plot

UAC board member Elliott Swann, his bodyguard Jack Campbell, and a recently transferred Marine arrive at Mars City, the main access to the UAC's Mars base. Sent to investigate multiple incidents involving the Delta Complex, Swann has a tense meeting with facility director Dr. Malcolm Betruger while the Marine reports to Master Sergeant Thomas Kelly for orders. Kelly orders the Marine to find a scientist from the Delta Labs who has gone missing. The marine finds the scientist in a decommissioned communications facility, where he is frantically trying to send a warning to the UAC on Earth about Betruger's teleportation experiments. However, as he tries to explain the situation to the marine, another teleportation test takes place but loses containment, at which point the entire Mars base is swept with a shockwave. The forces of Hell invade through the teleporter's portal and transform most of the base's personnel into zombies.

Now forced to fend off attacks from zombified base personnel and demons from Hell, the Marine returns to Mars City, where Kelly gives him orders to link up with another squad of marines and get a transmission card containing a distress call to the main communications facility to call for reinforcements. As the Marine progresses through the base, he learns that Swann and Campbell have survived and are also en route to the communications facility to prevent any messages being sent in order to contain the situation on Mars. The marine squad is ambushed by demons and slaughtered in the EnPro Plant, and although the Marine recovers the transmission card, he is too late to prevent the bulk of equipment at the communications facility being destroyed by Campbell. However, Kelly directs the Marine to a backup system, where the Marine is given the choice of whether to obey Kelly's orders to send for reinforcements, or accept Swann's argument to keep Mars isolated until the nature of the invasion is understood, so as not to endanger Earth. The Marine is told to go to the Delta Labs by Kelly or Swann, depending on whether the transmission is sent or not.
On the way to the Delta Labs, the Marine is contacted by Betruger, who is now shown to be working in cooperation with Hell in order to invade Earth. If the Marine did not send the distress call to Earth, Betruger does so himself, hoping to use the ships bringing reinforcements to transport the demons to Earth. Betruger then unsuccessfully attempts to kill the Marine using the toxic gases in the base's recycling facilities. Upon arriving at the Delta Labs, the Marine learns of the details behind the teleportation experiments, expeditions into Hell to retrieve specimens and Betruger's increasing obsession with the tests, as well as of a xenoarchaeological dig under the surface of Mars. The dig is excavating the ruins of an ancient civilization discovered on Mars and has produced a relic known as the Soul Cube. According to a scientist the Marine finds in the labs, the Soul Cube is a weapon created by the ancient civilization to defend against the forces of Hell. The scientist also reveals that the invasion began when Betruger took the Soul Cube into the portal at the beginning of the game, depositing it in Hell. The Marine pursues Betruger through the labs, but is pulled into the main teleportation portal after being lured into a trap by Betruger.
The portal takes the Marine directly into Hell, where he proceeds to fight his way through a large number of demons to the Soul Cube, defeating its demonic guardian. The Marine is then able to reinitialize the teleportation equipment left by previous research expeditions and return to the Delta Labs. Betruger, however, tells the Marine that although the main UAC teleporter has been destroyed, Hell is opening a Hellmouth on Mars, capable of bringing millions of demons to Mars. The Marine encounters the injured Swann, who informs him that Kelly has been working with Hell for possibly the whole time, and has been transformed by the demons. Telling the Marine that Campbell has gone after Kelly, Swann gives the marine his PDA containing information on the location on the Hellmouth under the surface of Mars and says that he will try to make his way out of the base alone.
However, when the Marine catches up with Campbell in the central computer processing sector of the base, Campbell is mortally wounded; before expiring, he says that Kelly has taken Campbell's BFG 9000 weapon. Kelly then begins to taunt the marine in a demonic voice. The Marine eventually faces off with Kelly in the central computer core, revealing Kelly has become a cyborg grafted onto a tank-like base. The Marine is able to kill Kelly and takes the BFG 9000 before proceeding deeper under the Martian surface to Site 3, the archaeological dig site where the Soul Cube was unearthed. At the primary excavation site, the Marine discovers the Hellmouth, defended by Hell's mightiest warrior, the Cyberdemon. Using the Soul Cube, the Marine defeats the Cyberdemon, and the Soul Cube then seals the Hellmouth. The ending cut scene shows the reinforcements from Earth arriving at the base to discover the carnage. They find the Marine alive but discover that Swann has died from his injuries. They are unable to locate Betruger, who in the final scene is shown in Hell, reincarnated as a dragon-like demon.



The Lost Mission

The player takes the role of the last surviving member of Bravo team, which was seen being ambushed by demons in Doom 3. The Bravo team survivor is contacted by Dr. Richard Meyers (voiced by Paul Eiding), a scientist working on teleportation experiments in Exis Labs, and asked to help Meyers destroy an experimental teleportation array that was captured by the demons and is currently held deep inside Hell. The array is potentially powerful enough to send an army of demons all the way to Earth, hence Meyers' desperation to destroy it. To achieve this goal, the marine must acquire the components necessary to activate the Exis Labs teleportation system, then travel to Hell in order to destroy the teleportation array. In the epilogue, the marine is teleported by Dr. Meyers back to Mars. The reinforcements from Earth arrive to search for another marine who is still missing; eventually, they find him in the Delta Labs complex.