The Plutonia Experiment (Series)

Doom: The Plutonia Experiment is a series of horror novellas written by Mike MacDee (Impie), based on the original Doom. It is comprised of three first-person stories told in an epistolary style (i.e., a collection of documents) which dramatize the events of Doom's three original episodes: Knee Deep in the Dead, The Shores of Hell, and Inferno. It incorporates and expands upon the story featured in Doom's instruction manual, but also features a few nods to Doom 3, such as the PDA and sentry bots, as well as references to the Doom Bible, such as the names of Sarge's security team.

In contrast to typical Doom and the operatic Doom novels, Doom: The Plutonia Experiment focuses heavily on the horror and psychological aspects of the Doom premise. The stories are notably nihilistic in tone, thick with gruesome imagery, and always end badly for the "doomed" protagonists.

Knee Deep in the Dead
The first entry in Doom: The Plutonia Experiment, based on the shareware episode of Doom. A research facility on Phobos is ravaged by a demonic invasion, and a lone space marine struggles with his sanity as he tries to escape the doomed moon. It is the only entry in the series that features the Doomguy as the main protagonist, referred to as "Sarge" -- in the subsequent entries, he is a peripheral character. It is also the only story that centers almost entirely on a single narrator.

Matthews
Nothing is revealed about his background, except that he was part of the rescue team sent to investigate Phobos Base when Sarge's team failed to report back. Matthews's after-action report describes the ruined state of Phobos Base -- noting that it had apparently "gone through a small war" -- and includes a transcript of Sarge's journal which was found at the site. Matthews notes that Sarge himself is MIA.

Sarge
The main protagonist of the story, sent to Mars after assaulting a superior officer. His real name is never revealed, and his background is mostly inferred throughout his personal journal, which comprises the bulk of the story. He was a Marine Sergeant on earth before his demotion and transfer, and is apparently quite educated based on his writing abilities. He serves UAC Mars as the newest security officer in Captain Berenger's unit.

Sarge is solemn and cynical, partly due to his current situation -- transferred to Mars to avoid bad publicity -- and partly due to his post-traumatic stress disorder, having served in an unnamed war in Pakistan. He has friendly relations with shift-mates Max and Rowlins; it is loosely implied that Sarge and Max are occasional lovers. Because of his cynical outlook and low regard for officers, Sarge's relationship with Captain Berenger is rocky at best.

When Berenger's unit is sent to Phobos Base as extra security (to help contain a crisis that is never disclosed to the troops), Sarge is the only team member left guarding the shuttle; as a result, he does not experience Berenger's catastrophic first contact with the demonic invasion force, though he does listen to the carnage on the team's radio frequency. Sarge enters the base in the hope of finding Max, as she is the only one who can pilot the shuttle; from then on the narrative suffers several lapses of insane rambling, as Sarge recounts his increasingly horrific encounters with the demonic invaders and the disturbed / possessed members of his unit. He survives by using guerrilla tactics and exploiting the demons' lack of tactical combat experience. When he reaches Phobos Labs, Sarge pairs up with a neurotic Max, and also discovers the Phobos and Deimos teleportation experiments (using "slipgates") were the cause of the invasion, accidentally opening a portal to the demon realm. Shortly before the invasion, Deimos had vanished from the sky (also not disclosed to the troops, though Berenger knew about it) as it was dragged into Hell, and the demons plan to do the same to Phobos.

Sarge is eventually captured by the Hell Baron, tormented with visions of its hellish dimension, and left strung up in an improvised meat locker where he narrowly escapes being devoured by a bulldog demon. Driven by mania, revenge, and a sense of duty to his race, Sarge bloodily stops the Phobos invasion and slays the Hell Baron. Only then does he realize the demons were after the slipgate technology all along: he leaves his PDA behind as evidence of what transpired, sabotages the Phobos slipgate, then travels to the demon dimension in the hope of destroying the Deimos slipgate, even though it will mean being trapped in Hell forever.

Romero
The UAC chief, to whom Sgt. Matthews sends his report and Sarge's story. Romero briefly replies to Matthews, dismissing Sarge's story as raving mania, and the demon carcasses as possible mutations from Phobos Labs. He unwittingly foreshadows a demonic invasion of earth in his postscript.

"Mad Max" Barrett
A former Air Force helicopter pilot and Sarge's best friend on Mars. Max is one of several shuttle pilots who deliver supplies to and from the moon bases. She is described as very boyish-looking with a smooth, sexy voice. It is implied that she saw what happened to Janssen, and as a result she enters a perpetual state of neurotic fear whenever she sets foot on the moons. Max's rescue is Sarge's primary objective for the majority of the story, for reasons both personal (he genuinely cares for her) and practical (she's the only shuttle pilot).

Unbeknownst to Sarge, Max has been twisted into a servant of the Hell Baron (she always seems aware of a greater power observing them). She convinces him not to regroup with Berenger, keeping the surviving human forces separated -- when Sarge discovers her betrayal, he impulsively guns her down.

Captain Berenger
The tall, blonde-haired, blue-eyed leader of the Mars Patrol unit in which Sarge serves. He is a gung-ho military man who responds swiftly and brutally to insubordination. For the most part, Berenger seems to tolerate his men's antics as long as they follow his orders to the letter. Berenger is a different man after the slaughter of his team: badly shaken and driven slightly insane by his encounters with the possessed humans and other, more horrible things he only makes cryptic mention of.

Berenger becomes possessed by a Death Head and nearly kills Sarge in a surprise ambush, but is killed when his helmet disengages in the vacuum of space.

Rowlins
A fellow marine, Rowlins is one of Sarge's close friends on Mars, besides Mad Max. He is a soft-spoken man who uses prayer to ward off his personal demons, stroking his cross pendant and muttering prayers whenever he is badly upset. He refuses to discuss his combat experiences as a result of his PTSD. When Sarge is reunited with him, he has suffered the torments of hell including having his eyes gouged out by the Hell Baron, and foreshadows the Baron's awful telepathic powers, as well as the hellish nature of the invaders. He then pleads with Sarge to give Rowlins his pistol, only for Rowlins to shoot himself in the head.

Janssen
One of two space marines whose deaths have become whispered legends on Mars, the other being Carlyle. According to video files discovered by Sarge, Janssen was used as a guinea pig in the early human tests of the slipgates, and was likely coerced into participating. His first and only trip through the slipgates immediately caused his raving psychosis, whereupon he gouged out his own eyes and died of shock.

The Shores of Hell
The second entry in Doom: The Plutonia Experiment. It has the most epic scope of the three books: spanning three narrators, and depicting events that take place before, during, and after those of the first book.

The survivors of the Deimos Base invasion -- and the dimensional relocation of the moon itself -- make several bold attempts to contact earth and alert humanity of what has happened.

Senior Science Officer Valerie Jackson
Jackson is the director of Deimos Base. She is only physically described by the burn scars on her face and hands, the result of a botched slipgate experiment; the other two narrators praise her as a wise and level-headed leader. She writes in a very formal style.

Jackson's tenure as narrator is brief: she describes a number of odd and unsettling events that eventually culminate in the demonic invasion of Deimos Base, and then the transference of the moon itself to the demon realm (though the Deimos personnel are unaware of their exact location, or that they've even left martian orbit). At this point her writing is quickly reduced to horrified rambling before it is cut off altogether. The Hacker later finds her skin being used as a wall decoration in a notably demonic part of the base; the method of her actual death is uncertain.

The Hacker
The first protagonist, who discovers the PDA of Jackson. His name is never revealed, but his prowess with electronics suggests that he served on the Deimos maintenance staff prior to the invasion. His segment comprises the majority of the story, and though he eventually deduces Deimos has been relocated to another part of the cosmos, he never learns exactly where it ended up.

The Hacker is a self-deprecating former alcoholic who is estranged from his wife, Ellen, as a result of his psychological issues, and his feelings for her swing between solemn resentment and borderline worship. Throughout the story, the Hacker is tormented by dream-visions of Ellen as she is horrifically abused by the forces of hell, seen from the perspective of her tormentors.

During the initial invasion, the Hacker escaped into the air ducts and made his way to a storage room, where he hid until the carnage was over, shaken by the gruesome slaughter of his coworkers and wracked with survivor's guilt. He records his experiences in Jackson's journal as a form of therapy, hoping to find Jackson during his exploration of the ravaged base; as such, he addresses Jackson at the beginning of each entry. When he learns of Jackson's death, he addresses them to Ellen for the remainder of his segment.

After surviving a harrowing encounter with a demon colony -- inhabiting a portion of the base which has been twisted into hell's likeness -- he seeks shelter in the Deimos Chapel, and finds a small colony of survivors hiding there under the supervision of Captain Fairchild. The Hacker is eager to find the Deimos slipgate, seeing it as their only way home; Fairchild, however, keeps everyone prisoner in the chapel, forcing a prayer routine upon them, in the hope that God will hear their pleas. He mercy-kills those who try to leave the chapel, to save them from a more gruesome fate at the demons' hands. The Hacker befriends space marine Brody and fellow technician Jerry, which whom he escapes to the computer station, where they reunite with Fred Harrison, another techie.

Fred formulates a plan to contact Mars Base by rebooting the nuclear plant, thereby rebooting the faulty communication systems. The first attempt fails as the Cyber-Demon reveals its presence on the moon, obliterating Fred before he can reach the plant. The Hacker narrowly makes it back to the team's hideout alive. A second attempt via the sludge-filled waste tunnels is only slightly more successful: the Hacker reaches the nuclear plant, but Brody and Jerry are devoured by Floaters in the process. In the Hacker's final entry, he condemns Ellen's emotional abandonment of him, but promises to find her and save her. Shortly after, his final and most horrific encounter is with Ellen, now a cybernetic monstrosity, who murders her husband on sight. His death is witnessed by the Unidentified Deimos Scientist.

Unidentified Deimos Scientist
The second protagonist, whose name is also never revealed. He narrates the last segment of the story, providing the plot's only closure. For the most part his writing is straightforward and concise, like a memo.

The Scientist is a member of the Deimos Labs science team who disguised himself as a Possessed Human during the invasion: as a result he has managed to move freely among the demon ranks, but expresses his regret at having to aid the demons in the butchering of his comrades in order to remain undetected. The Scientist hears the psychic commands of the Mastermind, but suspects that she knows he is an impostor, as she frequently forces him to assist in the gruesome cyber-experiments at the Tower of Babel (perhaps for her own amusement).

The Scientist initially justifies the crimes he has committed against his own race by recording his observations in Babel, with the hope of using the modified Deimos slipgate to return to earth and warn humanity. When he recovers Jackson's PDA and reads her journal (and that of the Hacker) he is distraught by the revelations they contain: that there were other survivors he could have joined up with, and that the woman he'd watched the demons torture in their labs was his friend Ellen. He resolves to stop the horrors of Babel once and for all, and returns to the anchored Deimos to recover Jackson's notes, without which he can never hope to configure the Deimos slipgate.

On Deimos the Scientist finds evidence that Sarge (from Knee Deep) has been there: the Cyber-Demon has been felled with a rocket launcher, all human corpses have been respectfully laid to rest, and supplies are stockpiled in caches around the base. Once inside however, he has a near-lethal run-in with a mob of Shit-Imps, the revived Cyber-Demon, and a wandering Death Head. Despite facing immense odds and suffering from terrible burns, the Scientist slays the Cyber-Demon and returns to Babel with Jackson's notes. His final entry explains that he has set the slipgate to do what it had done to Deimos: Babel will be teleported to Deimos's last known position, and everything inside the tower will die in the vacuum of space. Redeemed, the Scientist is overwhelmed by the demons shortly before his plan succeeds, though its success is only implied.

Ellen
The Hacker's estranged wife, a botanist at Phobos Base. The Scientist describes her as having Greek heritage and a love of literature. The Hacker is tormented with dream-visions of Ellen being brutally tortured and subjected to horrific experiments in Babel, little realizing that he is seeing her actual fate in real time courtesy of the Mastermind. Even as a cyborg abomination she regrets the death of her husband, and is mercy-killed by the Unidentified Scientist.

Brody
A space marine serving on Deimos Security. Brody is described as unusually pretty, but hard-headed and emotionally distant. She goes on several misadventures with the Hacker, usually acting as his bodyguard despite her partner's army training. Though tough and resourceful, she meets a terrible fate in the sludge tunnels beneath the nuclear plant.

Jerry McCabe
A Deimos technician who saw a portent of the impending invasion, but was detained as a lunatic when he tried to warn the others. He is distant and quiet for the most part, shaken by his ordeals with the demons and his fellow humans. He is nearly sacrificed to God by a desperate and insane Fairchild, but escapes his fate with the Hacker, only to meet a worse one in the sludge tunnels.

Fairchild
A security captain and cordial friend of the Hacker, Fairchild is the leader of a small colony of survivors taking shelter in Deimos Chapel, and serves as the human antagonist of the story. He presents himself in a naturally friendly and boyish manner, but this veils the madness and desperation boiling inside him. He believes the invasion is proof that Judgment Day has come, and tries to sacrifice Jerry for the survivor's sins. A firing squad of Former Humans inadvertently stops him.

Inferno
The third entry in Doom: The Plutonia Experiment, and the final chapter of the initial demonic invasion. It takes place several months after the events of the first two books. Though it is the second book to feature audio logs of the main cast (the first being Knee Deep), Inferno's audio logs are much more prominent, comprising half of the narrative. It also has the longest-surviving and perhaps most developed cast of characters.

A squad of marines and scientists is sent into the demon realm to recover stolen UAC technology, but instead uncovers a terrible conspiracy.

David Carver
The compiler of the story's documents and author of the forward and afterward. Carver is a scientist employed by the UAC, who embarks on several "descents" into the demon realm, now codenamed Inferno. He writes in an eloquent, borderline Gothic style to his friend Michael Delgado, a UAC coworker, describing his exploits and his growing concerns about the UAC's apparent abandonment of his team -- a fear which is confirmed by the contents of Inferno Team's mission log, which the "Doomed Marine" left for him to find. It is implied that he eventually escaped with Michael Delgado's help.

The forward makes it clear that the story was compiled as evidence of a UAC conspiracy, and suggests that his life may be in danger for its impending exposure. However, the documents are never used as such: the afterward describes the invasion of earth already in progress.

Major Urich
A US Marine Major who wrote the after-action report for the failed Operation: Inferno. Inferno Team was allegedly sent into the demon realm to destroy the quantum accelerator: a prototype slipgate device used for closing Inferno portals at will, which was stolen by the Mastermind's legions (along with the entire Plutonia Labs HQ). After a month of no contact with Inferno Team, the mission was considered a bust, and the quantum accelerator lost to the demons. Urich's report is later revealed to be mostly a lie, and the entire mission simply and excuse to send Inferno Team into the demon realm as sacrificial lambs.

Chief
The main protagonist and captain of Inferno Team. His mission log tells the bulk of the story, and reveals the truth behind Inferno Team's purpose. As with all the previous protagonists, his real name is never revealed, but he is described as a man of Cherokee descent who favors the use of a magnum revolver. His battles are the most vividly described of all the narrators, likely due to his lengthy military career (and resultant numbness to carnage).

Chief is an experienced US Marine captain who has commanded companies of soldiers in an unspecified war on earth for the past twelve years; he also commanded one of the marine companies present at Dr. Mohrig's development of the accelerator. He commands his troops with a drill instructor's bravado and frequently makes sarcastic remarks when speaking to them. However, he is a dangerous case of combat burn-out, exhausted by war and embittered by the Inferno assignment, having been promised that his tour of duty was over on earth. Inferno Team is to be his final command, after which he will return home and spend some much-needed R&R with his wife and three children, all of whom he misses desperately. As a result he is determined to accomplish Inferno Team's mission with ruthless abandon.

When Inferno Team discovers evidence that other teams were sent to Inferno before them, their contact with earth is abruptly severed, stranding them in the demon realm. Chief vehemently disregards the mounting proof that they have been sacrificed to the demons of Inferno, and that the whole mission is a sham. His desire to see his family again drives him to commit terrible acts against his teammates: he abandons Olsen during a scouting mission when he becomes a liability, and murders Dr. Parker when she tries to make him see the truth (and continually reminds him of his wife with her presence).

Alone and spiraling into madness, Chief eventually meets the Doomed Marine face-to-face, who further relates the UAC's betrayal and leads Chief to believe that he is a witness to Parker's murder. Chief plans to kill the Doomed Marine after helping assassinate the Mastermind, once the 'Marine has shown him how to return to earth. The assassination is successful, but the 'Marine -- aware of Chief's imminent betrayal -- tricks him into opening the control center roof and exposing himself to a mob of Floaters, which swarm and devour him. Chief's body is lost when the 'Marine blows up Plutonia Labs.

The Doomed Marine
The Doomed Marine is a legendary US soldier who has lived in the demon realm for a year, operating as a one-man recon and guerrilla unit. After six months of running official recon missions for UAC Earth, all contact with him was lost, and he was presumed dead, despite occasional "sightings" by descent teams.

The Doomed Marine is in fact Sarge from the original story: he has had several run-ins with doomed descent teams prior to meeting Inferno Team, and has deduced the UAC's secret alliance with the forces of Inferno, hence why he dropped off their radar. He has since been on a mission to assassinate the Mastermind and her clones, to cripple her demonic legion once and for all.

Living in Inferno and fighting for his species has given Sarge a sense of purpose he couldn't find on earth, hence why he has remained there. His run-ins with UAC assassins have taught him to deal with treacherous humans as well: he discovers Chief's plan to murder him after secretly reading his mission log while he sleeps. Following the Mastermind's assassination and the destruction of Plutonia Labs, Sarge recovers Chief's PDA and leaves it for the next expedition to find, with a note absolving Chief's actions and blaming the UAC for what he'd become.

Dr. Michelle Parker / "Slim"
A Plutonia Labs scientist, and lab partner of Dr. Olsen. Parker is a young black woman in her mid-twenties, the younger and more timid of the two scientists; however, as Inferno Team's situation worsens, she becomes stronger and more vocal, especially against Chief's increasingly callous decisions. She is problematic for Chief, as she is a spitting image of his wife back home, with whom the captain has had severe marital issues as a result of his military career.

Dr. Joss Olsen
The elder of the two scientists, Parker's colleague, and later the tertiary antagonist. He has apparently visited Inferno once before while testing another accelerator. He appears to have a very polite and friendly demeanor with everyone. Olsen grew up with his father, a Norwegian hunter, and thus knows how to clean and prepare animals for food. Late in the story, he becomes a violent "berserk pack" addict and nearly murders the surviving Inferno Team members, but dies wrestling a Hell Baron.

Sergeant Eric Borg
Inferno Team's equipment expert, and longtime war buddy of Chief. Borg is a beefy man who acts as the team's second-in-command: he addresses the younger marines more harshly than Chief does and seems less patient with their antics. He is repeatedly denied the chance to use the team's heavy weapons, to his everlasting disappointment. Like the two privates, he is ritualistically converted into a Former Human, all of whom are slain by Chief during the escape from the demon compound.

Private Gretchen Adams / "Retch"
Adams is the only female of the four marines on Inferno Team, described as being in her early twenties and sporting a face tattoo. She frequently giggles, seems to enjoy riding fast cars and using heavy weaponry, and often puts her well-being at risk to prove herself. She appears to know Ellison personally: they work well together in combat situations and joke with each other frequently.

Private Mitch Ellison / "Caveman"
Ellison is an Inferno Team marine in his early twenties who seems to know Adams personally -- they may have come from the same unit or grown up together. He appears to have trouble with women (as evidenced by Adams's remarks about his sex life) and, like Adams, doesn't always think before he acts. He is something of a flirt, joking with the female members of the team while remaining mostly serious with the male members.

Chief Engineer Thomas Mohrig
The head engineer of Plutonia Labs and inventor of the quantum accelerator. Mohrig was used as the UAC's disposable mouthpiece to forge the pact with Inferno, and now serves the Mastermind as a living database on quantum accelerator mechanics, dismembered and racked on the wall in the demon compound where the Mastermind freely accesses his memories.

Col. Warren / "Sweet Home"
Warren is a Marine Corps colonel who once served with Chief, and is now Inferno Team's handler on earth. He is notably humorless when he speaks, perhaps remorseful over his role in Inferno Team's fate. He severs their earth contact when the team discovers evidence of another insertion team, after having accidentally led them straight to it. It is possible that he had meant to lead them to the demon compound directly.

Game Comparison
Knee Deep expands on the original Doom story: Sarge is transferred to Mars for insubordination, listens to the slaughter of his teammates, then finds himself stranded on Phobos with a demonic invasion force hunting him. It ends on a similar note to the shareware episode, with Sarge going into the demon realm to the lost Deimos Base.

The plot of Shores is mostly original, as there was very little plot to Episode 2 apart from the big reveal that Deimos is stranded in the demon realm. Part of the plot tries to explain the bizarre changes that have overtaken the base architecture, and the origin of Doom's cybernetic monsters.

Inferno is based largely on Final Doom, concerning the stolen quantum accelerator. It ends on the same note as Episode 3, with the demonic legion ravaging earth.

All of the original Doom weapons are featured throughout the series at one point or another. The BFG 9000 is prominently featured in Inferno, not unlike the original IWAD. Mars Patrol is supplied with pump-action shotguns, an obsolete model that suggests their supplies are hand-me-downs. The more questionable weapons have their presence explained, or at least implied: chainsaws are used for butchering meat, and rockets used for clearing out rock during base expansion. The rocket launcher is always described as an. The standard weapon of Inferno Team is the M9, a reference to the generic rifle carried by Doomguy and Zombiemen.

Using the Berserk Pack has the same effects as the game: it heals the user and grants them tremendous strength and stamina for extended periods. It additionally makes the user aggressive and psychotic, and is followed by a terrible withdrawal period. Stimpacks are also featured as small medical kits used for emergency healing.

The antagonist of each novella is the boss monster of its respective episode, though only one Hell Baron is featured in Knee Deep.

In each novella, the story unfolds through the journals of UAC employees, much like Doom 3.

Levels
Several maps from all three episodes are featured throughout the series. Their descriptions more or less coincide with their counterparts in the game. Sarge even has a habit of criticizing the bizarre architecture of Phobos Base as he traverses it. Some of the memorable examples:


 * The sectors of both moon bases are referred to by their respective map names (Hangar, Command Control, etc). Most of the locations visited by Inferno Team are named by the marines, themselves, as they are conquered.
 * Phobos Base retains all the buildings referenced in the shareware episode, with the addition of a residential sector. However, all of the buildings hug close together and resemble a downed space hulk. It still spans the center of a huge crater.
 * The Hangar is Sarge's entry into Phobos Base, and has a similar layout to the game map. The outdoor nukage pool is covered by a plexiglas dome.
 * Command Control is the center of all Phobos Base operations, and its central hub is similar in design to the Blue Key room, though it is an elevated computer platform instead of a cage.
 * Phobos Anomaly vaguely retains its wand-like shape, but it is a top secret laboratory, so named for the strange experiments rumored to go on inside. The slipgate platform is similar to the area housing the Bruiser Brothers. It is also the scene of Sarge's final confrontation with the Hell Baron, where the building is blasted open, exposing itself to the moon's surface -- not unlike the end of its respective level in the game.
 * Deimos Base is a mishmash of human, demon, and organic architecture, a possible side-effect of its transferrence to Inferno. The Hacker describes the demonic changes to the Command Center in vivid detail, in particular the large marble carvings of demonic faces.
 * Deimos Chapel is a reproduction of E2M1, with more prominent religious iconography.
 * The Scientist names the Mastermind's inhuman laboratory the Tower of Babel. The Hacker witnesses its construction in dream visions, referring to its gradual construction on the intermission screen.
 * Inferno's sky is thick with blood-red mist, as in Episodes 2 and 3, and its landscape is a mixture of stone and organic matter.
 * Hell Keep appears almost exactly as it does in Episode 3 of the PC version of Doom. Soon after leaving, Inferno Team battles a demon squad in the Slough of Despair, which better resembles a slough than the original map.
 * Like its respective map, Pandemonium, the demon compound in Inferno is a twisting maze of corridors and stairways that lead in circles, and is inhabited by Hell Barons. The outdoor area near the player spawn is featured prominently, as is the long flickering hall with the secret bridge area, and a hall of cells similar to the starting area of the map.
 * Dr. Mohrig is held captive in what appears to be the House of Pain, specifically the closed-off area with all the crucified corpses.

The UAC
The Union Aerospace Corporation is the megacorp which is omnipresent throughout all three novellas, as they supply the technology and staff members inhabiting Mars and its moon bases. The UAC has considerable control over earth's space exploration programs, as well as the United States Armed Forces. It is the secondary antagonist of Inferno, and in some ways the primary villain of the entire series: it is the UAC's avarice, carelessness, and technology that leads to the demonic invasions of Phobos, Deimos, and ultimately Earth. It is suggested in Inferno that the UAC has killed, or attempted to kill, in order to protect its dark secrets.

Slipgate technology was developed by the UAC's Plutonia Labs division in the hope of expediting space travel, allowing ships to instantly teleport from one gate to another regardless of distance between the gates. Unbeknownst to UAC executives, the slipgates had torn a rift between earth's galaxy and that of Inferno, drawing the attention of the ambitious Mastermind. In Inferno, it is revealed that the UAC had seen a business opportunity in the demon realm: they forged a pact with the Mastermind, offering advanced earth technology and human lives (for experimentation, possession, and mind-reading) in exchange for a monopoly on supernatural artifacts. This deal carelessly armed the demonic legions with the weapons they needed to overtake the earth. The UAC presumably fell during the final invasion.

Demons
All of the monsters from the original Doom are featured as the antagonists of the series. For the most part, they preserve the appearance and abilities of their original incarnations. Despite the human characters' interpretations, the invaders are never explicitly proven to be demons, nor their homeworld to be the biblical Hell. Their true origin (and for the most part, their hierarchy) is never revealed.


 * The Mastermind is the primary antagonist of the series, and supreme commander of the demonic invaders. Throughout Shores and Inferno, its presence is felt or "heard" through invasive telepathic projection, but it never makes a physical appearance until the last chapters of Inferno, when it is killed by Chief with a BFG 9000.  It resembles a giant, flabby mass with a piranha-like mouth and two fist-sized, red, serpentine eyes; when confronted at the end of Inferno, it has been given six cybernetic spider-legs, presumably to help it move about. By the end of Inferno, Sarge / the "Doomed Marine" reveals that the Mastermind has cloned herself: he has four dead clones to his credit, but an unknown number remain.  Should he kill them all, the demon legions will fall into disorder -- this, and Carver's closing words, are the only glint of hope left to the reader by the series' end.


 * The Hell Baron, also called the Devil of Phobos, is a minotaur-like demigod who serves as the invasion's field marshal, and the main antagonist of Knee Deep in the Dead. During his vision of the demon realm, Sarge describes him as a member of the "goat-god" race, which appears to be superior to the majority of the realm's denizens.  He exhibits overwhelming mental powers such as clairvoyance, pyrokinesis, and an invasive form of telepathy that can subjugate creatures and computers.  The Devil of Phobos is responsible for all the atrocities committed on both Phobos and Deimos, and is killed by Sarge at the end of Knee Deep when the roof is blown off the Anomaly, exposing the beast to explosive decompression. Another Hell Baron inhabits the demon compound in Inferno, harvesting and guarding the Mastermind's human offerings; it dies in a bloody stalemate wrestling a berserked Dr. Olsen.


 * The Cyber-Demon is the secondary demonic antagonist (next to the Mastermind) of The Shores of Hell, which prevents the human protagonists from escaping the stolen moon. It is a towering cybernetic monstrosity: a hybrid of demon and machine which was created as a living weapon.  The beast's organic parts are in constant pain, which is part of the cause of its constant, violent aggression. Its left arm is a fearsome dual-weapon combining a heavy gatling gun with a multi-shot rocket launcher.  It is slain by the Unidentified Scientist with a rocket launcher.


 * Death Heads (or Lost Souls) are demonic skulls wreathed in fire than swim through the air like fiery sharks. They have the horrific ability to "leap inside" of a living creature and take over its body, reducing it to a cannibalistic maniac. They make their most prominent appearance in Shores, and are only described in the other two novellas.


 * Possessed Humans -- often referred to as "zombies" despite being intelligent beings -- appear to have full access to their dead host's memories and knowledge, as they prove capable of understanding (and even engineering) complex human technology with astonishing speed. This makes them the most integral part of the invasion, which requires the modification and theft of the UAC slipgates.  They typically serve the same purpose as when they were human: possessed space marines are put to work as armed patrols, and possessed scientists slave away in the labs. They communicate in a hideous, gibbering language, but exhibit poor organizational and tactical skills. Several key characters become possessed throughout the series, most notably Captain Berenger of Mars Patrol, and Borg, Adams, and Ellison of Inferno Team.


 * "Shit-Imps" are six feet tall and burnt-brown in color, with bony spikes on their backs and shoulders. Sarge describes their faces as "just jaws and teeth", with two beady eyes that glow in the dark.  They have the inexplicable power to throw fireballs like percussion grenades; Chief notes that the creatures use fire to subdue their prey, which they then eat alive. Shit-Imps are the most prevalent demonic species, and evidently serve at the front line of the invasion, appearing in hordes during the initial moon assaults; afterward, when the Possessed Humans take over, their numbers greatly diminish to small groups of stragglers.


 * "Bulldogs" are large-headed, gorilla-like beasts with raw pink skin and bull-like horns, named for their dog-like howls and snarls. They appear several times in large numbers throughout the series, usually assisting the Shit-Imps on the demon realm's front line during the moon invasions.  They attack by charging forward to latch onto their prey with their jaws, even when doing so causes them more harm than good.


 * "Floaters" (Cacodemons) are among the most fearsome of Inferno's demon species due to their ability to fly, their unnervingly stealthy approach, and the devastating lightning attacks they sometimes use to kill prey at a distance. Every story in the series features at least one "floater" scene, most notably the Hacker's doomed voyage through the cramped waste tunnels in Shores, during which his remaining friends are devoured by the beasts.


 * "Spectres" are briefly encountered by the Hacker and Brody on a failed recon mission in Shores. They are described as being transluscent like jellyfish in the water, and almost completely invisible in darkness. Fairchild cryptically alludes to them in one scene; they later drag the priest Mathis to his death.

Criticism
Knee Deep and Shores were relatively well-received on Doomworld and Fanfiction.net in 2008: they were praised as being truer to the source material than the official fiction, though the original version of Shores was criticized as the weakest and shortest of the three. Inferno was eventually finished and uploaded in 2013; an expanded revision of Shores was uploaded in 2016. Doomguy's relative absence from the second and third installments was considered a major factor in their lukewarm reception.