Doom, Doom II, "Doom"note Images taken from Doom Wiki user Fraggle
The Doom series is a 1995 collection of novels written by Dafydd ab Hugh and Brad Linaweaver.Yes, somebody wrote a series of novels based on Doom. Yes, thatDoom.Knee-Deep in the Dead is the adaptation of the first game. Corporal Flynn "Fly" Taggart is a US Marine fighting terrorists in Afghanistan when he punches out his lieutenant to prevent a massacre. He's arrested and pending court martial, but the next day his company is shipped to Mars to investigate a distress call from the Union Aerospace Corporation. Fly listens in horror to his comrades and friends being killed by unknown enemy forces. He takes down his guards and, armed with only a pistol, enters the mining facility to save his friend PFC Arlene Sanders.Cue the "demons", Satanic architecture, and ultra-violence. Fly and Arlene slog their way through Phobos and Deimos fighting armies of demonic-styled alien monsters.Hell on Earth is the adaptation of Doom II. The aliens have arrived on Earth and the world governments have collapsed. Fly and Arlene crash land a rocket from Deimos and meet with one of the last bastions of resistance: Salt Lake City. They join with a Mormon sniper, Albert, and a teenage hacker, Jill Lovelace, on a mission to steal enemy intelligence from Los Angeles and deliver it to the resistance military base in Hawaii.Infernal Sky is where the novels start to jump off the rails. Fly, Arlene, and Albert have a new mission with a new member, Esteban Hidalgo, to return to Phobos. Friendly aliens have made contact and a Gate on the moon will allow the team to meet the aliens in person. The masterminds behind the "demons" are revealed: a race of broccoli-like aliens nicknamed "the Freds".Endgame is when the novels almost completely abandon the Doom franchise. Fly and Arlene have been shanghaied on a one-way, suicide visit to the Fred home world. On arrival they find that the Freds have been wiped out. The pair finds a member of the race that killed the Freds and try to regroup with the rest of humanity.While they are both adaptations of the video game, the novels are a completely different beast from the comic. There is no RIP AND TEAR here.
These novels provide examples of:
Accidental Pun: Arlene and Albert are going to Radio Shack to find computer connectors. When they arrive she tells Albert that they shouldn't have any problems finding the jacks for Jill. She catches it and starts giggling and it takes Albert longer to get the pun.
Afraid of Needles: Fly, capable of blasting "demons" back to Hell and having swam through toxic sludge, comes up with excuses not to give himself an injection that may keep him alive.
Alien Invasion: The demons from hell are really terror-soldiers genetically engineered by aliens.
Alien Sky: The aliens "rework" the Earth sky to their liking, this also has the side effect of cancelling most of the radioactive fallout from the nuclear war.
All Webbed Up: Bill Ritch was wrapped in webs after the spidermind interrogated him.
Almost Out of Oxygen: Fly and Arlene are trapped on Deimos with a hole in the pressure dome. It's a large facility so it takes over a month before the air is running dangerously low.
Amazonian Beauty: Fly describes Arlene as being the best looking woman he's ever seen, but not in the conventional sense of beauty, in particular he loves her muscle tone. One newbie to the squad once tried to pull down her pants, the whole squad was interesting in seeing more of her ass but weren't stupid enough to piss her off.
And I Must Scream: A very real threat to all sentient life except for humans. Their consciousness remains inside their corpse, unless the body is completely destroyed, and all of their senses remain functional. Where ever they drop will be the last things they will ever experience for eternity if nobody is around to retrieve them. Efforts are made to Defy the trope, the dead are recovered and placed in theaters to be entertained. This fate is a given for those unfortunate enough to be captured by the enemy, as they will be endlessly tortured with no hope of saving themselves.
Appeal To Audacity: Albert believes that Fly and Arlene aren't enemy spies because their story of riding Deimos to earth, defeating that wing of the invasion, and building a rocket to crash on earth is too ridiculous to be an effective lie. Lampshaded by Fly, who thinks that spies should be telling absurd stories if that's the trick to trust.
Earth suffers a Human Die-Back. The Freds and their monsters have devastated all nations and humanity is struggling from the ruins to prevent extinction.
Fredworld suffers a Planetary Desolation at the hands of the Newbies. Fly and Arlene arrive and it takes them over half a day to even find a corpse to resurrect. Arlene is the first one to notice the planet is completely silent and desolate.
Artifact Title: Infernal Sky starts to do away with the Doom elements. Endgame has nothing to do with the games aside from a simulation of the Phobos base.
The Old Ones who built the Gates also created gravity fields on Phobos and Deimos. The UAC makes use of them and builds their facilities around them.
At one point, Fly wanders into a zero-G section and has to pull himself along with a handrail. He rounds the corner and finds a trio of imps walking on the ceiling and walls. How they're capable of doing so is a mystery.
Humanity, under Newbie influence, masters artificial gravity to a degree that the Old Ones couldn't: humans can install gravity fields on ships.
Ascended Extra: On the cover of the original Doom there is a second space marine in the distance running to join Doomguy in the foreground. The authors gave him a sex change and created the second protagonist Arlene Sanders.
Bag of Spilling: Justifying the games, where every episode begins with the player armed only with a pistol. The teleporters between bases, the "episode" breaks from the games, destroy inorganic material. So Fly and Arlene arrive at their destination naked and unarmed and find clothing and a pistol shortly after. After they crash-land on Earth, the transition from Doom to Doom II, the only things lost in rocket crash are the guns.
Battle Couple: Eventualy, Albert and Arlene. However, they never fight together as a married couple, Albert's wounding and inability to finish the mission was the catalyst for Arlene marrying him.
Bavarian Fire Drill: Fly and Arlene want to report to the Marines but the Mormons don't trust them yet. They bully their way to a radio by acting like an inventory sergeant and his assistance on a tour of inspection, complete with a Clipboard of Authority.
Belligerent Sexual Tension: Albert and Arlene. They're reluctantly attracted to each other shortly after they meet. Albert tries not to argue with her but Arlene hates the Mormon church, blaming it as part of her brother's downward spiral, so she picks fights and challenges his beliefs. Eventually, after a few missions together, they start flirting and the point of contention becomes their mutual sexual attraction. Arlene is willing to sleep with him but Albert's faith forbids pre-martial sex, and so the religion arguments continue.
BFG: The old Trope Namer itself. Fly has no idea what kind of gun it is and calls it "the big freaking gun".
Big Red Devil: The hell princes, aka barons of hell, are giant red minotaur-like monsters.
Bizarrchitecture: Justifying the games. The secret doors are explained as motion sensor-controlled automated sections of the mining facility. Then the aliens start altering the place to terrorize the humans. Fly and Arlene aren't sure if the aliens are responsible for a computer bank built as a Nazi Swastika. Later they find the region of hell they're in is laid out as a giant hand.
Blackout Basement: The lights in the facilities are often off or broken. However, the true Blackout Basement is a maze on Deimos with a field that tampers with energy. Flashlights can't penetrate more than a foot into the darkness and night-vision barely functions. Fly and Arlene try a Dungeon Bypass but can't find the key card off the floor without investigating the maze.
Bloody Bowels of Hell: A favorite form of reworking the Martian facilities: spread flesh all over the walls.
Bluff The Eavesdropper: The squad meets the infiltrators who make the zombification serum. The chemists blast obnoxious loud music and talk about bands and drugs with the heroes while the real conversation is held on note pads.
Bookcase Passage: Fly finds the escape route of the chemist's basement hidden behind a bookcase. There was a fake book to operate it but the bookcase was blown to pieces before he could figure it out.
Boring Return Journey: Fly and Arlene kill the spidermind at the bottom of the huge Deimos facility. Then they hike back up the whole place finding mountains of corpses and enemies too crazed to put up any resistance.
Boss Battle: The first fights against the cyberdemon and the spidermind are boss battles, with a massive arena that the fight takes place in, just as they were in the original game.
Canon Name: The game's "Doomguy", meant to be the player, is Fly Taggart in the books.
Chainsaw Good: Arlene chooses an unexplained chainsaw on Deimos to clear a hallway of demons. This nearly gets her killed. Fortunately, it goes far better the second time.
Knee-Deep in the Dead: Fly and Arlene are trapped on Deimos, Earth is being invaded, and their air supply is running out. But Arlene has a plan to get them to Earth.
Hell on Earth: Fly and Arlene are trapped on the 40th floor of the Disney building, enemies pounding at the door, and Jill and Albert flying for Hawaii. But Arlene has a plan to get them down and to Hawaii; involving duct tape, computer wiring, and "the biggest goddamn boot" he can find.
Infernal Sky: Fly and Arlene (see a pattern here?) are trapped on board the Fred ship with no way to alter its course and heading for the Fred homeworld. But Arlene hates Fly for going too far and taking them centuries away from their war and her husband.
Clipboard of Authority: While still under suspicion of being enemy spies, Fly bullies his way to a radio by writing "notes" on a clipboard and acting like he's inspecting the facility.
Les Collaborateurs: The US government surrendered to the aliens and compose most of the forces attacking Salt Lake City.
Cut the Juice: Arlene's plan to escape the Newbie computer: kill the power running the simulation. When Fly brings up the point that killing the computer they're trapped in may kill them as well, Arlene just shifts tactics to finding the connection out of the simulation and into the main computer.
Deadpan Snarker: Everyone. If sarcasm and smart-ass could kill monsters the invasion never would have progressed past Phobos.
Death by Transceiver: Fly and his idiot guards listen to PFC Grayson fighting and being killed by a monster.
Dungeon Bypass: Subverted. Fly gets fed up with hunting for key cards and fighting monsters over them so he blasts a door open with a few rockets. This is the only locked door he ever destroys: he meets the barons of hell shortly afterward and they can withstand four to fix rockets a piece. From that point on rockets are reserved for emergencies and "boss fights" and he and Arlene run the dungeons looking for key cards. One time he suggests the option to Arlene to avoid entering a maze of unnatural darkness to find the key. Their rocket supply is dangerously low so they brave the dark maze instead of risking taking the next baron without ammo. They encounter a baron in the maze and they kill it for the key. Running the dungeon cost them all their rockets when the Dungeon Bypass would have used a few.
Enemy Civil War: The different species of monster turn on each other very quickly, especially when under friendly fire. Fly believes there is a single intelligence that keeps them on the same side and sometimes it loses its grip on the minions. In particular, barons of hell and cacodemons loathe each other, the first proof being a cacodemon nest decorated with crucified barons.
Exactly What It Says on the Tin: Fly asks Arlene what they should call the flying skulls. Arlene simply replies "flying skulls". Fly takes it as a question, confirms that he's encountered flying skull monsters, and asks again for a name suggestion. To which, Arlene replies:
"Flying skulls, you lamebrain! Call 'em as you see 'em".
Exorcist Head: The talking imp rotates its head as it lays dying and talking to Fly.
Exploding Barrels: Just like the games. Fly learns about them by accident: he's pinned down and his shot goes wild, hitting a barrel and clearing the room with the chain reaction.
Friend or Foe: The monks in the prologue are only shadows in a dense mist. Arlene, the company scout, reports that they're unarmed monks but Lt. Weems panics and refuses to listen to her. When Fly fails to knock Weems out, the lieutenant gives the order and Fox company massacres the non-combatants.
Gag Penis: Twice Fly and Arlene find a bas relief of a hulking demon with an enormous penis that serves as a lever.
Fly and Arlene finally return to Earth after nearly five hundred years, hot in pursuit of the Newbie/Resuscitator ship planning on "fixing" humanity. The enemy never arrives and they never find out why. They land at the rebuilt Salt Lake City Tabernacle where an AI construct of Jill is waiting. She confirms their identities and welcomes them inside to receive a gift: a teenage clone of Jill and a black box on a card table with a card reading "Albert". The end.
Albert! Albert?! I didn't know what to say, so, Goddamn it, I decided to just shut up and be a Marine. Semper fi, Mac... I know when I'm beat!
A duplicate Fly and Arlene slog through the Deimos facility looking for a backdoor out of the Newbie computer system. They find the door and open it, finding the soul of a Newbie, and kidnap it back into the simulation as the Newbies pull the plug. The hyperactive evolution overclocks within the system and they will the Newbie to evolve out of the physical dimension. They have no idea if they banished one or somehow all of the enemy species, it turns out they did and that is why the enemy ship never arrives. The pair realizes that, barring a miracle, they're trapped inside the simulation forever. Fly and Arlene resolve that they can will their new reality to be better than the original by ending the invasion before it lands. Arlene hopes she can un-remember Albert's death so she can be with him again. The end?
I awoke to a brave new world that had such damned peculiar creatures in it!
The Guards Must Be Crazy: A pair of bored Clydes are frisking zombies boarding a plane. They fall to notice the heroes faking undeath or catch that one of them is being carried upright on board.
Arlene falls apart for a bit after having to kill her reworked lover Dodd. She had asked Fly to do it for her if she couldn't but realized that she'd hate him if he did and chose her living friend over her dead lover.
The second time Arlene breaks down is worse. Dodd was a lover but she otherwise didn't understand her feeling for him. She truly loved Albert and married him. And Fly's berserk rampage on the Fred ship robs her of returning to her husband, even if he's aged forty-years. She wanders the Fred ship in a daze, her only communication with Fly is to mourn Albert, tortures the dead Freds by using them as target practice, and fires into the bulkheads without caring about a ricochet killing her. The only way Fly can snap her out of it is to walk into her line of fire.
Humans have the awesome power of being Killed Off for Real. When the human body dies the consciousness/soul ceases to exist, or goes somewhere, but a dead human is gone. All other sentient life has their consciousness remain trapped in the defunct body with all of their senses still functioning. They can hear if they're being spoken to or feel pain if somebody abuses their corpse. Resurrection is simple enough but it's possible that there isn't enough remaining of the body to succeed or it's not a priority for others. The dead are rounded up and stored in amphitheaters where operas and other performances are held to entertain them pending a resurrection.
All other races suffer from Medieval Stasis. They evolve and progress at a staggeringly slow pace. When the Freds scouted Earth they arrived at the end of the Middle Ages, saw a Catholic-dominated world armed with swords, and made centuries of invasion plans based on humanity remaining at this stage of development for thousands of years. They never could have anticipated mankind having nuclear weapons and early space-flight within six hundred years.
I Am Not My Father: Fly's motivation for joining the Marines and his love of the Corps. His father was a cruel, petty criminal lout with no sense of honor or dignity. In the Marine Corps Fly could be everything his father wasn't.
I Know What You Fear: The spidermind can transmit horrible images or retrieve them from the minds of humans.
Ideal Illness Immunity: Arlene gave Jill a sex ed talk during the LA mission. She's lamenting afterward that humanity had beaten STDs, including AIDS, just for aliens to wipe out most of the species.
Improvised Weapon: Arlene likes to make creative use of things around her. First was her Chainsaw Good moment on Deimos. On Earth, she uses a fire extinguisher to surprising effect on an arch-vile. Fly wonders if he can nominate her for an "improvised weapons commendation".
Indy Escape: The only way to cross a pool of "lava" is over a wooden plank bridge which starts to collapse as they cross it.
Insignificant Little Blue Planet: Earth is nothing more than the move of a pawn in a six million-year old war. The only reason friendly aliens are helping out is because they're bleeding hearts and don't want to see even insignificant life get stomped on.
It's Raining Men: Defied. The Marines want to dive out of the Navy ship and drop on Phobos rather than risking a landing. The pilot vetos the idea because her job is to do everything in her power to get them safely to the surface.
Live-Action Escort Mission: The LA mission is to steal enemy intelligence and deliver it to Hawaii. Translation: escort Jill to the enemy computer so she can hack it and get the intel. They were concerned about the girl being a liability, and she does make some teenager / civilian mistakes, but she's smart, dedicated, and has enough combat experience to keep out of trouble.
Madness Mantra: Some of the zombies can speak but all that comes out is ominous gibberish about the Gates, "Great Ones", and death.
Magnetic Weapons: The Fred ship comes under railgun fire when crashing on Skinwalker. This frightens Fly as last he had heard about railguns they would destroy their target and then suffer a catastrophic meltdown. If the Newbies have functional anti-ship railguns then they have already surpassed human technology.
A Million is a Statistic: Fly and Arlene watch from space as the earth is carpet-nuked. They aren't nearly as disturbed by this as they feel they should be, until they start thinking about specific people they know who are probably dead.
Mondegreen: As Fly and Arlene are being connected to the Newbie computer simulation, he sees Arlene mouth a message to him: "Patrick". Fly has absolutely no idea what she's trying to convey with that message or how it could help them, all that comes to mind is the story of Saint Patrick who converted the Irish. Once in the computer, he decides to trust Arlene and attempts to convert the monsters. He succeeds and rallies a growing army of the enemy, awed by his Reality Warper powers. Once they regroup in the computer, Fly learns that she said "battery", as in "Cut the Juice".
Mythology Gag: As noted under Bizarrchitecture above, at one point Fly and Arlene comment on a computer bank shaped in the form of a Nazi swastika. This was present in early versions of the original game as a reference to Wolfenstein 3D.
The Neidermeyer: Hidalgo starts this when when introduced to Fly and Arlene. He instructs them that he's not going to fraternize with them, demands proper uniform maintenance, and tells Fly that almost saving the world nearly makes up for punching his last CO. Fly's natural dislike of officers, their experience with Lt. Weems, and the high stakes of the mission lead Arlene to suggest killing Hidalgo if he's a liability.
Nice Job Breaking It, Hero: Fly and Arlene decide to report to their CO after arriving in Salt Lake City. They trick the guards to let them use the radio and tell their story. Then they're arrested as traitors to the species because the entire US government surrendered to the aliens. If the enemy didn't already know that Salt Lake City was a resistance bastion, the pair are prime targets after they defeated the Deimos wing of the invasion. The attack comes in two hours and is predominately human forces.
No Celebrities Were Harmed: Sci Fi enthusiast Forrest J. Ackerman makes an appearance in Infernal Sky as the chief xenobiology scientist. He befriends Jill and makes her part of his research project but gets killed because of a zombie breakout.
No Gravity for You: The first cyberdemon is killed by luring it out of the Artificial Gravity and tricking it into firing its missile launcher. The inertia launches it against the chamber wall and smashes the creature, "like a supermarket being slam-dunked into a mountain".
Noodle Implements: Hell on Earth ends with Arlene and Fly trapped in a building with the monsters, and Arlene asks Fly to get "some duct tape from the toolbox, an armload of computer switch wiring, and the biggest goddamned boot you can find!". Subverted in Infernal Sky, which opens with Fly and Arlene relaxing on the beach, giving their companions conflicting accounts of just how they used those objects to escape.
The Not-Love Interest: Arlene and Fly are only buddies. They got drunk one night and kissed but found it too awkward.
The Nudifier: The Gates destroy inorganic material passing through them, meaning Fly and Arlene wind up naked on the other side.
Omniglot: The Newbies can learn languages impossibly fast. Fly asks if Arlene has the Newbie covered and the alien figures out the vocabulary and language structure immediately. It speaks better English than Sears and Roebuck by the third question and has mastered the language within an hour.
One-Man Army: Fly and Arlene. Both of them survived nightmarish odds on their own. Together they rip apart a small moon of alien monsters.
Our Zombies Are Different: They are capable of firing guns, deranged speech, and can follow orders. Like all the monsters they have a hair trigger and go berserk if hit by friendly fire. Most never blink and Fly believes that's the reason for their poor accuracy. Some are capable of basic tactics like taking cover. Zombies also have a rotting lemon odor which may be linked to some manner of chemical that induces a berserker rage in men. The zombies also require air to breath, a plane full of them dies when the air is purged.
The Password Is Always Swordfish: Lampshaded by Fly in the Newbie computer. There is an eleven character password to open the backdoor out of the system, and like a smartass he attempts "PASSWORD___". He is stunned when it works and then he mentally rages at the idiot who would do such a thing, given he attempted as a joke. It could be actually be Invoked by him given as he and Arlene have Reality Warper powers while in the computer.
Playing with Fire: The arch-vile is protected by a field of heat that prevents bullets from hitting it and heats the firing gun to dangerous levels. It can also focus its power to produce devastating explosive heat blasts.
Fly is caught in the Room Full of Zombies and he slowly shambles his way through them unnoticed.
After coating themselves in rotting lemons, Fly and the gang start shambling their way through LA. Jill comes dangerously close to blowing cover by exaggerating her Zombie Gait with arms outstretched and stiff like Frankenstein's Monster.
Reporting Names: Shortly after they reunite Fly and Arlene start brainstorming names for the monsters. They hope to find a radio and they want to provide a proper report on what they've encountered. It's also the closest thing they have to entertainment. Arlene is better at the game and usually comes up with a reason to assign a monster the proper name from the games. Those that differ are:
Baron of hell - hell-prince
Cacodemon - pumpkin. Later on, the military formally designates the monster as "cacodemon".
Clyde is the name assigned to the vat-grown humans and fills the role of the chaingun zombies. Fly doesn't get the reference to Clyde Barrow, and he asks why they don't call the clones Fred and Barney or Ralph and Norton.
Revenant - bony
Mancubus - fatty
Arch-vile - fire-eater
The Mormons have their own conventions using Biblical/demonic terms. The only confirmed name, by an Albert POV chapter, is moloch for cyberdemon. A force of "brownies" and "baphomets" attack Salt Lake City; brownie is almost certainly the imp and baphomet is probably the demon, as both are the grunts of the alien monsters. "Shelobs" are mentioned in the same vein as moloch-cyberdemons, the biggest and most powerful of the monsters. Given the name comes from The Lord of the Rings, shelob is probably the spiderminds.
Room Full of Zombies: Fly steps off a lift and finds himself in a Room Full of Zombies so jam-packed that they don't notice him.
The Sneaky Guy: Arlene is the unit's scout and Fly describes her as being a ghost. When they reunite Fly learns she managed to sneak past a number of encounters he had to blast a path through.
The late "Dude" Dardier changes hair color over ten pages. She's blonde when first mentioned and has red hair when found.
An imp talks to Fly early in Keep-Deep in the Dead. This is a minor plot over the series and becomes a major plot point in Endgame. However, there was a second talking imp the first book. All it did was crack a bad joke but this is never mentioned again. Every time the subject of monster intelligence comes up, "that talking imp" was the only time it ever happened so far as the characters are concerned.
Twice Fly and Arlene encounter Gag Penis switches and both times they react with surprise.
Jill's last name changes between the second and third books. She's Hoerchner in Hell on Earth and Lovelace in Infernal Sky and Endgame.
Fly nicknamed the imps "spiny" in the first book, Arlene demanded to call them "imps". After Infernal Sky, both POV characters repeatedly insist that it's Arlene who calls them "spiny".
At the end Infernal Sky, the heroes are unarmed and naked after teleporting disintegrated their weapons and clothes. At the start of Endgame, they have their uniforms and weapons back. They didn't find replacements nor they didn't make new ones. The authors even call attention to it: Arlene laments losing her wedding ring because it disintegrated with their gear.
The non-disintegrated Endgame weapons are different weapons than they had in Infernal Sky. And these guns are now their weapons of choice when they preferred the original set.
Jill changes hair color between the second and fourth books. She's a redhead in the second book and blonde in the last. Dardier in reverse.
Hidalgo's wife was said to be killed by a Hell Prince in the first few chapters of Infernal Sky, but later on in the book, this changes to a Steam Demon instead.
Set a Mook to Kill a Mook: Just like the games. Fly learns that the monsters go berserk from friendly fire and uses it to his advantage whenever possible.
After the first "pumpkin" dies an extremely messy death, Arlene shouts "smashing pumpkins into small pieces of putrid debris". This is a nod to the game's no-clip cheat code: IDSPISPOPD.
Fly makes a comment about how dangerous and weird the facility is, saying that any random door may have machine gun-toting Nazi Schutzstaffel behind it. This is a reference to the secret levels of Doom II that recreate levels from Wolfenstein 3D, complete with machine gun-toting SS.
Fly and Arlene, with Bill in tow, find themselves repeating the first area after they left the hyperspace tunnel. Arlene says "Deja", Fly follows with "Vu", and Bill quips "Dejah Thoris". Arlene catches the reference to John Carter of Mars and snickers.
Sneeze of Doom: Bill Ritch sneezes while the gang is trying to sneak around the spidermind's army.
Staking the Loved One: Arlene and Fly find that Arlene's lover, Wilhelm Dodd, is now a zombie. She freezes at first and Fly prepares to kill him. Before he can, Arlene steels herself and guns down her lover. They both knew that Fly killing Dodd would be the end of their friendship and Arlene did the unthinkable to protect that.
Pistol: Fly steals a pistol from the guards. After teleporting between bases, naked and unarmed Fly and Arlene keep finding pistols before anything else. The novel also attempt to Justify the rifle-equipped zombies dropping pistol ammo in the game: Fox company's standard weapon is a single-shot 10mm rifle nicknamed the Sig-Cow and the rounds are interchangeable.
Shotgun: Fly was desperate for one early on, he finds a few from dead comrades.
Automatic: Instead of the chaingun from the games there is the AB-10 machine pistol.
Rocket launcher: One that fires D-cell battery sized rockets to justify the game allowing Doomguy to carry fifty rockets.
BFG: Fly finds the original BFG in the "hell" sections of Deimos.
State Sec: The IRS has it's own "revenue collection" army.
Super Smoke: The really weird cloud monster that wasn't in the games. It attacks the squad as they're surfing onto the beach, first it's a thick fog that descends into the water and then it's a thick cloud obscuring a large mass with fangs or claws. The submarine kills it before they get a good glimpse or even really engage it.
Switching P.O.V.: The first novel is told entirely from Fly's point of view. From the second novel onwards the POV switches between Fly, Arlene, and occasionally the supporting characters. Jill gets an odd chapter in Infernal Sky that's third person instead of first.
Tonto Talk: The spidermind is digging in Fly's head trying to find some horror or trauma to stop him. It digs up the most humiliating event in his life: the day his father, at a Hawaiian museum, yelled "Me heap big chief Kamehameha!" by a statue of the beloved king.
Trail of Bread Crumbs: Arlene borrows an idea from Journey to the Center of the Earth and leaves a trail of her initials and arrows showing her route through the Phobos facility. Fly recognizes the marks because she introduced him to the movie. She also shares the initials "A.S." with the character who left the trail: Arne Saknussen.
True Companions: Fly, Arlene, Albert, Jill, and Ken become a close little family unit during the LA mission. Even when Ken was effectively luggage during it. Part of why Hidalgo is resented when he's sent on the Phobos mission and Jill is left on Earth.
Unstable Genetic Code: Newbies in a nutshell. All sentient life aside from humans and Newbies take thousands of years to evolve or progress. Humans are blindingly fast, able to progress from sailing ships to inter-system star ships in a mere five centuries. The Newbies managed to advance from hunter-gatherers to a force able to destroy the Fredworld in half that time. They evolve so fast that the dead one found on Fredworld fears he's now a different species after forty years separation from his kind. When Fly finally tries to kill him, the Newbie starts evolving new organs to reroute around the damage caused by bullets. When Fly and Arlene catch up to them on Skinwalker the Newbies have become microscopic and have infected a human fleet. This becomes the Newbie's downfall, they drag the soul of a Newbie into the computer simulation and the processing speed accelerates the evolution until it disappears from the dimension.
William Telling: Gunny challenges Arlene over her haircut and he shoots an apple off her head. She earned the respect of the squad by not flinching a bit, then doubles it by doing the same to Gunny.
Womb Level: Some of the worst reworking of the Martian facilities replaces the human architecture or natural stone with pulsing, fleshy structures. After the Deimos Gate they find themselves in an actual giant womb.
You Didn't Ask: The squad crosses the LAX parking lot planning on hijacking a plane and they only briefly discuss which of the Marines is going to fly it. None of them know how to. They hijack the plane, enemies pounding on the cockpit door, and are trying to decide on who's going to make the attempt when Jill volunteers. When asked why she didn't speak up before, she says "You didn't ask."