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Just maiming and injuring can also occur, however.
"On the last day of August, London turned into a Killing Floor."

"I told you, I am welding this doah!"

A cooperative online Zombie Apocalypse First-Person Shooter for PC developed by Tripwire Interactive on the Unreal Engine 2. Originally a mod for Unreal Tournament 2004, in 2009 an official retail version was released. While generally an updated version of the mod, there are changes - notably the "perk" system, a series of seven different "classes" that players can choose.

You and up to five friends take the roles of a squad of a bunch of surviving military, police personnel, street thugs, the Pyro, a Queen's Guard, and more sent into various areas to wipe out the Specimens of a Freak Lab Accident Gone Horribly Wrong. Games are divided into several rounds, in which players must kill a required number of specimens. Between rounds, the players have a minute (or ninety seconds on Beginner difficulty) to visit the Trader, a woman who sells you weapons, armor, and ammo. After all the set rounds are completed, one last round against the Patriarch, the creator of all the specimens, who has become a genetic monstrosity himself, happens. The game's story is not exactly a masterpiece, but it has an obvious goal.

If the basic premise sounds like anything familiar, it's totally different, and in fact the original Killing Floor mod came out first (2005, versus both of the above first coming out in 2008); if anything, it has more in common with the zombie-focused Counter-Strike mods that also inspired Left 4 Dead and Call of Duty Zombies, considering its wave-based gameplay and that killing zeds accrues cash which, between waves, can be spent at a designated location to upgrade your gear and replenish your supplies.

A top-down shooter spinoff of the game titled Killing Floor: Calamity was released on the Ouya on December 18th, 2013, with an Android port following after. On May 8th 2014, PC Gamer announced a sequel, Killing Floor 2, is in the works. An Early Access build of the sequel was made available on April 21, 2015, with a full release following on November 18, 2016. A third game was also announced in 2023.

Has a modest Shout Out page.


Lots of lovely tropes, just waiting for you:

    open/close all folders 

    # - B 
  • Abnormal Ammo: The Buzzsaw Bow and the Flare Revolver, two DLC weapons, are respectively a crossbow that shoots circular sawblades and a big revolver that shoots flares. Halloween 2013 DLC added a leafblower that sprays acidic Bloat bile and an apparently scratch-built weapon that launches exploding harpoons.
  • Actually a Doombot: Transit (Objective Mode) confirms without a shadow of a doubt that the Patriarch has been cloning himself as well.
  • All There in the Manual: The entire plot, centering around a leading stem cell researcher, CEO, under-the-table-unorthodox-science-military-applications-expert, and doctor of bio-genetics and engineering named Kevin Clamely, whose research became less than practical after the murder of his son.
  • Alternate Reality Game: Killing Floor was one of the 13 indie games that formed the bulk of the material of Valve's "PotatoFoolsDay" Portal 2 ARG, which in its case resulted in a new map based on the testing facility from Portal and GLaDOS as that map's Trader.
  • A.K.A.-47: Zig-zagged. There are things like the AA12, SCARMK17, MP5 and M4, and at the same time there's the "Handcannon" (a Desert Eagle), "Bullpup" (an L22), "Schneidzekk" (a Kriss Vector SMG) and "Combat Shotgun" (a Benelli M4). And, similar to most other games with an AK, the game's version is referred to as simply the original AK-47, but is actually a shortened Romanian variation. Of note is the promotional image for the Golden Handcannon(s), which refers to it/them by the Desert Eagle name.
  • Amusement Park of Doom:
    • The summer Abusement Park map, complete with freakshow skins for the Zeds and Creepy Circus Music.
    • Hellride and the Steampunk themed Steamland maps.
    • ThrillsChills, the very last official map released by Tripwire, features an underground Christmas-themed park.
  • Apocalyptic Log: A lot of the level descriptions are this, explaining what happened for the area to be overrun by specimens. Mostly this revolves around the specimens moving into an area, then slaughtering everyone within it with the team being sent to clean up or try to Hold the Line. Others mention the aftermath of your team's helicopter going down in an infested area, with specimens closing in on you.
  • Arm Cannon: The Patriarch's preferred method of problem removal, and the primary weapon of the Husk.
    • And with the Twisted Christmas 2011 update, you can use the Husk's arm cannon as a weapon yourself!
  • Armor Is Useless: Averted in normal gameplay, where body armor protects from at least two-thirds of the damage from anything other than a Siren's scream, but Gameplay and Story Segregation makes this the case for a few characters who visibly wear heavy gear/armor that does nothing useful - the description for Lee Baron even specifically mentions that specimen claws and teeth tear right through his EOD gear.
  • Artifact Mook: Some maps, especially Suburbia, which takes place in a small American town thousands of miles from the Horzine labs. Since the specimens have no way of infecting others, this means that hundreds of them somehow crossed the Atlantic Ocean. This becomes even more confusing when the Patriarch appears, since his presence essentially means that all of the specimens somehow crossed the ocean. The map Icebreaker, taking place on a large cargo ship, could technically explain this, however.
  • Artificial Brilliance: Specimens will actively move to avoid hand grenades. Husks aim their shots to impact the ground near their target, similar to a human player with a rocket launcher. And, in an example verging on Artificial Stupidity, specimens will sometimes jump for the hell of it, just to throw off a player's aim. And speaking of behavior that's situationally stupid, most of the specimens seem to avoid approaching players in a straight line if they're already part of a large group so they can flank better. And sometimes, the Patriarch might fire his rocket launcher prematurely, giving little time to take cover.
  • Artificial Stupidity: Pathing for the specimens can make them suddenly change their mind about what direction to run when chasing players. This has been abused to make the Patriarch attempt to run and heal by trying to blow up a welded door in the same room as the players unloading into him. Bonus points if the door he came through is still open, moreso if he had only just passed it before attempting to run and heal.
    • Speaking of pathing, the floating light that leads players to the trader likes to spin around like a drunk instead of pointing players in the correct direction if they don't stop moving for a second to let it get its bearings. And in extreme cases, it may point players towards a path that leads to them hurting or even killing themselves if they follow it, such as skipping a set of stairs entirely by jumping over the side or pointing towards an open window on the third story of a building.
  • Ascended Meme:
    • One of the Circus Scrake's lines is "And not a single fuck was given that day".
    • The inclusion of a Loadsamoney Expy named Harold Lott, who leaves a trail of money behind him as he walks. He also costs $5 by himself, compared to all of the previous character DLC packs which are $2 for a pack of 4.
  • Ax-Crazy: The Specimens aren't so much as dumb as they are bloody insane. The Siren (in the original mod) acted as if nothing was wrong and everything was sunshine and roses and was wondering why the nice young men were hurting her, the Scrake was meant to be a medic and would feel good while healing people, but found that braining blokes felt even better.
  • Awesome, but Impractical:
    • The Berserker perk can turn into this in later waves or higher difficulties - being up close and personal with that many enemies, in particular that many Fleshpouds and Sirens, gets you killed very quickly, nevermind fighting the boss. On the other hand, expert Berserker players can easily run circles around or even stunlock most Zeds, up to and including Scrakes, though teammates can interrupt the effect by shooting stunlocked enemies, and in turn the Berserker getting in close to Zeds to damage them means that he's liable to block the line of fire for other players.
    • Going Guns Akimbo often has this effect. You get double the fire rate and ammo capacity over using one gun at a time, which makes them handy for close encounters, but you sacrifice the precision of being able to look down the ironsights, meaning mid- to long-range combat will be much more difficult. The dual version of your starting pistol suffers the worst as it lacks enough damage to be of real efficience and weights four blocks rather than a second Deagle or a Magnum.
    • The MP7M and the M7A3 are both almost useless to anyone who isn't a Medic. The MP7 has light damage, a small mag size of 20, and an extremely slow heal dart recharge rate. While the damage for the M7A3 is much better, it weighs 6 blocks, has a small mag size of 15, and has the same heal dart recharge of the MP7. By contrast, the MP5M and the Schneidzekk are much better off perk, due to their heal darts recharging much faster.
      • However, the MP7M can be pushed to Difficult, but Awesome by a skilled player, particularly a Sharpshooter that wants some full-auto teeth. Careful trigger discipline can compensate somewhat for the absolutely absurd fire rate and Boom, Headshot! lower-end Specimens while saving the more expensive ammo of the Sharpshooter's dedicated weapons for real threats. While hideously expensive to non-Medics, the MP7 can be bought after the first round by a level 5 Medic (a level 6 Medic spawns with one).
      • The M7A3 and Schneidzekk also can venture into this territory. The former has damage similar to the MP5M while being fifty percent more expensive, and lacks the power to really go toe-to-toe with heavier-grade Zeds. It also has absolutely absurd recoil, making it difficult to hit anything on full-auto when waves get hairy. It also takes the fourth weapon slot whereas all other med guns take the third, making it harder to swap between the med guns if you choose to focus on healing everyone as the Medic. The Schneidzekk, on the other hand, has great damage, but a fire rate that borders on unbelievable and regular iron sights that block half the view when aiming and are hard to see in the darknote , compared to the other weapons' more open red-dot sights. It also goes for a hefty price even when well-leveled (and even used to be the most expensive weapon in the whole game during some time after its release).
    • The Combat Shotgun does the same damage per shot as the regular Shotgun, but is semi-auto instead of pump action, carries less shells, reloads slower, and costs more, which makes it better for taking down Scrakes and Fleshpounds than weak Zeds. While carrying 6 shells as opposed to 8 isn't much of a problem, the other two downsides are a bit extreme. Each shell reloads 35% slower (enough that both weapons take the same amount of time to reload from empty), and it costs five times as much as the basic Shotgun.
    • The FAL. Boasts the exact same damage per shot as the SCAR (save a bit more range), with the same ammo capacity, a longer-range sight, and with a higher fire rate, but costs £300-400 more and has a slightly longer reload.
    • The M99 AMR, in the hands of a high-leveled sharpshooter, can one-shot most enemies - including Fleshpounds! - at almost any difficulty level and go through a line of specimens like a hot knife. The downsides? It costs £5000 to fill up - but only holds 24 shots in reserve - making each shot cost £250. It's also a single-shot rifle with a reload time of at least 1.75 seconds, but the worst part is that it weighs 13 blocks - meaning that the only weapons you can carry alongside it is your starting pistol, knife and grenades (taking up a block in itself), and either a machete (a step up from the knife) or a pipebomb, neither useful for a sharpshooter unless in specific situations. It's only has some real use against the Patriarch - money serves no purpose after the next-to-final wave, and the only other specimens that spawn in the boss wave are low-tier things that a capable sharpshooter can easily take care of with their 9mm.
    • In fact a majority of weapons in the game are all around outclassed by something else at a similar price point.
      • Choice of pistol is largely irrelevant to a sharpshooter, a headshot is almost always a one hit kill and higher difficulty rounds can't be survived firing for the torso. The revolver is especially disadvantaged because despite its high damage, its rate of fire renders it so much worse than even the starting pistol that it's really only used to show off.
      • The berserker's axe and claymore are the only weapons capable of stunning scrakes on higher difficulties, no other weapon is useful. In fact the more expensive claymore has a less reliable swing arc and expert players almost universally prefer the fireaxe.
      • The M7A3 and MP5M's lower med-dart recharge rates make them useful only as a means to compensate for the medic's low ammo capacity.
    • The L.A.W. It can sweep off a whole group if it explodes, has extremely high damage with a huge blast radius, headshots with it still deal double damage, and it can finish off a Fleshpound in two hits. It also can't be fired without aiming down the sights, is the heaviest weapon in the game which leaves you no room to carry a sidearm, doesn't explode if it hits a target at close ranges (and sometimes at long ranges), thus dealing pitiful damage, has expensive ammunition, leaves the user defenceless in the presence of a Siren, needs to take a long reload period after a single shot, and needs to be shot from a safe distance in order to explode and actually deal any real damage without catching the user or teammates in the blast radius.
  • Badass Normal: It'd be easier to list who isn't one.
  • Bad Santa: The Christmas-themed Bloats and Patriarch.
  • Beat Them at Their Own Game: Two achievements related to killing Husks with fire-based weapons. The newer one fits better because the weapon involved is the same one they're armed with.
    • There is also an achievement for killing two Scrakes with the chainsaw, their signature weapon, in one wave.
  • Beauty Is Never Tarnished: The default Stalker model is surprisingly healthy-looking and attractive, lacking the deformities and disfigurement seen in most of the other specimens (only the Scrake also doesn't have bits sliced or decayed off). True, the hair on the left side of her head is missing, but it comes across more as an aggressive punk haircut than a medical disfigurement. Averted with the Siren, who is emaciated and missing her eyes.
  • Berserk Button:
    • The Fleshpound does not appreciate being shot or having a line of sight on targets and not attacking them. It also doesn't appreciate it when it can't reach its target. Blood will rain like mist as it rips apart anything around it in a frustrated fury should a player find a spot it can't reach. This makes it difficult to earn cash since the player does not get money for specimens the Fleshpound kills.
      • This is actually a great way to win a round if you team is likely to die: if one person can glitch to an unreachable spot (and take out any Husks that approach) the Fleshpounds will basically act as a Mole, leaving only a few Specimens left to deal with.
    • Bored specimens will turn on each other, but very rarely.
  • The Berserker: The Berserker perk. With his brisk movement speed, absurdly thick skin and mighty swinging arm, he specializes in closing in on the Specimens and fighting at spitting distance, first with the humble knife or machete. Later, with some more dosh, he can keep up his nimble ways of dancing in and out of enemy range with renewed strength thanks to the fire axe, katana, or claymore, or become the world's most painful doorstop with a bloody awesome chainsaw.
    • On the specimen side, Scrakes, who swing wildly at a target with their highly-damaging chainsaws; and Fleshpounds, Scrakes on crack, who move slowly at first (but go into an unstoppable charge when sufficiently damaged), are capable of reducing players to mulch in a few hits.
  • BFG: Or "Big Sodding Gun", as several characters will comment when equipping heavier weapons like the LAW and the M99, but as of the 2012 Winter Event, we get a true example in the Zed Eradication Device (Z.E.D.) which fires lasers and can emit a field which significantly slows down and lowers the defense of any specimens caught within it. The catch is that you need to collect all fifteen parts of the weapon scattered around the "Moonbase" event map in order to use it, and even then it costs 2,000 pounds and, like the other heavy weapons, weighs a lot.
  • Big Damn Heroes: Can happen to you, or anyone for that matter.
  • Black Comedy: Pukey the Clown is a fan of this.
  • Blade Below the Shoulder: The Gorefast. The Scrake too, but with a chainsaw.
  • Bling-Bling-BANG!: One of the DLC packs released for the 2012 Christmas event allows players access to a gold-plated AK47, Combat Shotgun, M79 (complete with golden grenades), and Katana. A second pack for the 2013 Summer event adds the gold-plated Handcannon (with tiger-stripe pattern), AA-12, Flamethrower, and Chainsaw. The concept was then deliberately avoided for the 2013 Halloween event, with a new weapon skin pack instead adding properly-camouflaged versions of the Shotgun, M4, MP5M, and M32.
  • Body Armor as Hit Points: The Medic has this, as he gets 100% protection from damage to his health when he has a kevlar vest, in addition to taking less armor damage overall. Kevlar normally reduces damage to health by about 77%, with a few exceptionsnote .
  • Body Horror: The Summer Sideshow Gorefasts. Good Lord, how are they still alive with that many swords in them? And the Sideshow Crawlers, for those of you who like their Body Horror in the realm of medical possibility.
    • The Halloween Hillbillies also qualify, such as the Crawlers missing their lower bodies, or the Husk and Fleshpound having respectively a fireworks launcher and giant augers grafted to their arm-stubs.
    • Save for the Scrake and the Stalker, all the standard Specimens are also hideously deformed:
      • The Clot had its nose and genitals surgically removed, in addition to look emaciated and having several "entry ports" Matrix-style jammed in his body.
      • The Gorefast is completely skinned, has its left arm amputated at the elbow, and a blade jammed straight into its right forearm, splitting the hand in half. Its lower jaw has been removed, giving the Gorefast its characteristic hissing noise.
      • The Crawler is a human-arachnid hybrid, and the result is a sickly-grey creature with a man's body, the many eyes of a spider, and spindly spider legs sprouting out of its body.
      • The Husk is a Specimen with metal protrusions nailed all around its limbs, and what appears to be hooks pulling down the lower eyelids. Also, its skin is badly burned, revealing in some areas the musculature of the creature.
      • The Siren is an emaciated girl bound by a leather harness with her mouth sagging open, revealing irregular teeth. Her eyes have been ripped out, leaving nothing but dark gaps.
      • The Bloat is a jaundiced creature whose belly is swollen with vomit, and has a red and bubbly rash down the side of its belly and both of its thighs, most likely due to the Bloat's bile.
      • The Fleshpound is a seven-foot-tall muscular giant with spiked steel plates ornating his body and replacing his eyes and genitals, with rotating maces for arms and a biological pump strapped to his chest. The pump fills him with sedatives and tranquilizers in normal times, but if he's in danger or is frustrated by seeing a survivor without attacking them long enough, it switches to pure adrenaline and excitants.
      • The Patriarch is a bit taller than the Fleshpound, with tentacles pouring out of his chest and a severely swollen right eyeball that pops out of his head sometimes. And has a pornstache.
  • Boom, Headshot!: The Sharpshooter perk lives on this trope, but any bullet-shooting weapon can do it. Also of note: decapitations on any specimen (except the Patriarch) will remove its special ability if they don't kill it outright, as well as making them slower and eventually killing them due to bleeding.
  • Boring, but Practical: The 9mm Tactical you spawn with, while weak, is still useful for beheading low-level specimens, and it's one of the few weapons equipped with a flashlight. At higher Sharpshooter perk levels, it does increasingly respectable damage, nearing the point of becoming a viable primary weapon against all but the toughest enemies or fit for use on all but the hardest difficulties, where a specific damage reduction applies to it.
    • The Bullpup, the weakest assault rifle in the game, can still clean up a group of enemies and even, in the hands of a Commando or a skilled player, take out tougher enemies such as Sirens or Husks. And you can often find it laying on the ground.
    • The Lever Action Rifle (commonly abbreviated as the LAR). While slow-firing, it has decent power and it's the cheapest any-perk weapon in the game at £200, making it a good early-game sidearm. Unlike many of the other firearms in the game, it is loaded one round at a time, meaning a player can cancel reloading the full amount if they realize the sudden need to switch to a different weapon or run for their lives. Additionally, its headshot bonus is double the regular damage (moreso if you happen to be a Sharpshooter), compared to most other guns' 10% bonus, and as the rounds drag on, headshots are the only way to go. In the hands of a fully leveled Sharpshooter the Lever Action Rifle turns into downright Infinity -1 Sword capable of swiftly taking down any threat that is not Fleshpound on high difficulty or the Patriarch.
    • The Knife, which you also spawn with, is nominally a last resort weapon. Equipping it allows you to run faster, however, plus no matter what perk you choose, a hard swing or two to the neck of a Clot or Gorefast is still going to kill them immediately on any difficulty.
    • The Compound Crossbow seems out of place in a game full of high-end military hardware. But in the hands of a capable Sharpshooter (or pretty much any other experienced player regardless of their perk) it can tear the heads off of most Zeds with only one shot (the Fleshpound and Patriarch being the exceptions). It comes equipped with a scope (one of few weapons that do), and not only that, bolts can penetrate and kill multiple smaller Zeds with a single shot. Additionally, a maxed-out Sharpshooter will always spawn with this weapon. It has undergone several whacks with the Nerf bat, but since most of those have focused on its cost it still remains a strong weapon for those who can consistently shoot Zeds in the head. Just like the LAR example above, it becomes a full fledged Infinity -1 Sword if the high level Sharpshooter is using it, and it can be used against the Patriarch as well.
    • Regarding perks, the Field Medic perk is incredibly useful, especially on higher difficulty levels. As expected of a support class, you'll be spending a lot of your time trying to keep an eye on your teammates, and likely will spend a decent chunk of time sitting in whatever spot gives you a view of as many of them as possible. But being able to fire healing darts at range means you can easily patch up a teammate from a considerable distance so long as you can Lead the Target, and combined with gas grenades that heal any players inside the area of effect, a decent medic can pull the team through what would otherwise be a party wipe. At high perk levels they can spam healing darts for effectively unlimited healing by switching through two or three of their perk weapons, since each one has its own separate recharging ammo count. They're not that bad in combat either, gaining high speed and much more protective armor, and their mainstay perk weapons are rapid-fire automatic weapons that can do a decent job of cleaning up the weaker enemies (and on lower difficulties, rotating through multiple weapons as each runs dry one can potentially take down the tougher specimens).
  • Boss Banter: The Patriarch has a rather large list of lines. "Excellent, another batch of subjects!"
  • Bottomless Magazines: Not the usual application, but one of the bonuses for a high-leveled Medic player is that guns meant for that perk are given up to double their usual magazine capacity - leading to sights such as loading a 20-round magazine into an MP7 and then spitting out 40note , or managing to fit 64 bullets into an MP5's 30-round mag. Some other perks get the same bonus, but not to nearly the same extent (Commando weapons only get 5 to 10 extra bullets, for instance).
  • Breakout Character: For a game with an All There in the Manual plot, and characters that have no actual differences other than appearance and voice (there's a total of two voices for 46 of the 50 playable characters), DLC Mr. Foster seems to be slowly becoming the main character of the game.
    • Everyone loves Mr. Foster. Everyone. Unsurprisingly, he's one of the characters in the sequel.
  • Break Out the Museum Piece: The Halloween 2012 event adds a bunch of World War I and World War II-era weapons, including an MKb42, M1A1 Thompson, and M1897 Trench Gun loaded with incendiary buckshot. Owning the stand-alone Red Orchestra 2 expansion Rising Storm gives access to another Thompson with the famous drum magazine, and the Steampunk weapon pack includes dressed up versions of yet another Thompson and a scoped Lee-Enfield.
  • Breakout Mook Character: One of the playable characters in the original mod is Claire, a Stalker who was captured by humans and trained to fight on the side of humanity.
  • British Royal Guards: Captain Sir Richard Wiggins, a minor aristocrat with a commission in the royal guards. He sees specimen hunting as jolly-good fun. His outfit consists of his roughed-up and missing-a-sleeve red coat and fuzzy hat, with some pouches and holsters tacked on.
  • Bullet Time: Zed time, which occurs randomly when a player does something impressive, e.g. getting several headshots, taking down a tough enemy or scoring a kill at an absurd distance. Time slows for a short time, and multiple slowdowns can be chained by the Berserker and the Commando.
  • Butt-Monkey: Police Sergeant Davin is this, according to his background. He's been looking for a big change in his life. It's safe to say he got one. All hail the end of the world.

    C - F 
  • Calling Your Attacks: Played straight with the Patriarch, who utters distinct lines before his rocket or gatling gun attacks. Subverted when he turns invisible, charges, and without so much as a word punches a Combat Tentacle through your face.
    • Also done with the Fleshpound, which stops in place and screams angrily before charging at the players.
    • Not quite attacks, but player characters loudly announce every time they reload or heal another character with the syringe. They also comment on some of the higher tier weapons when they pull them out.
  • The Cameo: The RED and BLU Pyros from Team Fortress 2 appear as selectable character skins. See Crossover.
  • Chainsaw Good: Go ahead and guess what one of the best melee weapons is. The Scrake also has a chainsaw for an arm.
  • Character Class System: Seven "perks" are available and serve as the game classes. Each has their own requirements for level advancement, but the general benefits are increased damage/reduced costs for that Perk's associated weapons, which acts as a form of training for harder difficulties where money is scarcer and more skill required for survival:
    • The Berserker: Focuses on melee weapons and combat. Can run quite fast when wielding a melee weapon and is overall more resistant to damage. Properly used, they can act as a meatgrinder when holding a single defensive area, or superb flankers when situations call for running around the map and whittling the Zed count down.
    • The Commando: Good with all weapons, but shines mostly with assault and battle rifles, for which they get both damage and magazine increases as their perk level progresses. They can also see through the cloaking used by Stalkers and the Patriarch at close range, and can also see Specimen health bars within a given range as well.
    • The Support Specialist: Shotgun expert; getting more penetration and increased ammunition capacity. They also get increasingly more carrying capacity and un/welds doors faster.
    • The Firebug: Loves fire. A LOT. Inflicts much more damage with fire weapons and becomes more resistant to it, to the point of eventually being immune to all fire damage and starting a game with a free flamethrower.
    • The Sharpshooter: Shoots Specimens in the head with pistols or semi-automatic rifles. It hurts them. A lot.
    • The Demolitions Expert: Blows up Zeds with launched/thrown grenades and planted explosives; becomes increasingly explosion-resistant and eventually starts the game with a free M79.
    • The Field Medic: The healer of the group; still more than capable to pile up bodies with their frikkin' fast submachine guns. Also tied with the fastest runner on the team so they can catch teammates to heal them. Originally they used only a rechargable syringe to get the job done, but then dart-shooting medic guns were added specifically for them to use to do even better. Oh, and healing others gives a 60% reward in cash.
  • Charles Atlas Superpower: One of the Support perk bonuses is increased carrying capacity. And even then, other perks can carry their fair share of weapons and ammonote .
  • Christmas Elves: The Clots became goblin-like grotesqueries of this trope for the Christmas events.
  • Circus of Fear: The summer event's theme.
  • Cloudcuckoo Lander: The Scrake. While his lines can be hard to hear, they're... not exactly all that intimidating.
    "I like trousers."
  • Color-Coded for Your Convenience: The Fleshpound has a bizarre glowing... thing on his chest that Turns Red instead of yellow when he gets mad or takes enough damage in too short a time span. Player characters used to all be green and blue, too.
    • That 'thing' in his chest is an adrenal pump, and when he gets pissed, it... pumps adrenaline. Which leads to every player in-game yelling 'OH SHIT!' and running, emptying whatever weapon they're currently holding at it, or both.
  • Combat Medic:
    • Even if you go Field Medic, you're going to spend a lot of time shooting at Zeds, unless things start to go horribly wrong. In fact, the Medics are actually good in combat, since the Medic perk gives massive bonuses to your armor and faster ability to heal yourself, not just others.
      • A higher-level Medic can actually do more of the Combat part of the trope. At level five or above, most of his weapons have absolutely absurd ammo capacities, he spawns with armor (which for him acts as a second health bar), he gets healing grenades that cause a form of damaging area denial to Specimens, and his normal running speed matches the sprint speed of the Berserker. The weapons still don't put out enough damage to truly qualify him as a Lightning Bruiser, but a higher-level Medic can certainly mop up the lower-level Specimens with ease in between topping off everyone's health bar.
    • The Scrake is meant to be the specimens' version of this. He's supposed to have been the ultimate field medic, able to take crazy amounts of punishment while saving the lives of other specimens (with amputations via chainsaw when necessary because why the hell not), but he only learns by being wounded himself and has taken an unusual fascination in dishing out and receiving pain.
  • Cool Mask: A large number of the playable characters wear some kind of mask, mostly gas masks.
  • Crazy Survivalist: According to his bio, Sergeant Powers lost his entire family to the specimens. Oh, and he collects freak fingers. Apparently, he disconcerts the rest of the characters, who are plenty crazy themselves.
  • Creepy Circus Music: The Summer Sideshow maps Abusement Park and Hellride feature variations of well-known melodies.
  • Critical Existence Failure:
    • The medic has upgraded armor and can thus take heavy amounts of damage. Once he loses that armor he's as fragile as the rest of the team.
    • The actual spirit of this trope is averted by the player characters, who move a bit slower when their health is at about 40, and even slower when that's halved, which is also accompanied by the screen becoming near-totally blood-red.
    • The Specimens all play this straight if you don't take off their head.
  • Crossover:
    • For the first Twisted Christmas event in 2010, anyone who owns both Killing Floor and Team Fortress 2 received a pair of Pyro player models for KF, and Mr. Foster's gas mask and tie for the Pyro in TF2.
    • Those who preordered The Ball received a player model of that game's protagonist Harchier Spebbington.
    • Killing Floor's involvement in the Alternate Reality Game surrounding the release of Portal 2 climaxed with the addition of KF-Aperture, a Portal-based map with things such as pressure buttons to open certain doors, Zeds using the apparatus delivery systems to get around, and messages to the player scrawled on the walls. When the ARG was still running, the Trader was temporarily replaced with what appears to be GLaDOS' Anger Sphere.
      "Well, it's been fun. Enjoy that thing you do. You know, dying."
    • To a lesser extent, there's one with Red Orchestra 2 in the form of Nikolai and George, obtained by pre-ordering or purchasing the Digital Deluxe edition. Doing so also gave you a Stalhelm and a Pilotka to use in Team Fortress 2. Similarly, the Red Orchestra spinoff, Rising Storm, nets players a World War II GI and a Japanese grunt.
    • The Twisted Christmas 2012 event adds a Dwarfs!? Axe to the game, which you can unlock by playing or buying that game.
  • Cute Monster Girl: Of all the Specimens encountered, the Stalker isn't as obviously mutated or mutilated; she mostly looks like a punk chick who got into a particularly bad fight and decided to forego most of her clothes. The same cannot be said of her Summer Sideshow or Halloween variants, however; at best, she's a Butter Face.
  • Damage Discrimination:
    • Players are Friendly Fireproof, though you still get hurt by any explosives you yourself deployed.
    • Fleshpounds do not play well with others, and don't appreciate other specimens being in the way of them and their target. Scrakes, meanwhile, don't enjoy being pushed out of the way by a raging Fleshpound. One plus one equals an enjoyable diversion. Other specimens are much more forgiving of inadvertent friendly fire, but do occasionally turn on their fellows.
    • The Bile Thrower was made to instigate this amongst the Zeds, since it uses drums of Bloat bile as an acid-thrower. If a Zed is doused in it while near a Bloat, it will hold the Bloat responsible and begin attacking it instead of you.
  • Deadly Doctor: Doctor Dave from the Steampunk DLC. He also has a nice hat (top hat, of course).
  • Deadly Lunge: The Scrake, the Gorefast and the Fleshpound all start rushing at you once they take enough damage or get close enough. The Crawler does a more literal lunge, attacking by leaping at your face.
  • Dead Weight: The Bloat is grotesquely fat, but he's not really a zombie.
  • Deadpan Snarker: The player characters are quick to call out specimens on how outrageous some of them look or act.
    • "A machine gun for an arm? No effin' way!" "He goes bloody invisible too?" "Rockets, too? Now he's really taking the piss." "Bloody hell, what's he got on his arms?" are just a few gems.
    • Some of the other responses qualify as well, be it berating another character for not holding still while trying to heal them or one of the voiceclips for asking for money: "Where's my bloody benefits check?".
    • And then there are the taunts, two separate commands for Zeds ("You're pathetic! Like a bunch of bloody Millwall fans!") and teammates ("Who do you think you are, bleedin' Action Man?")
  • Defector from Decadence: The Lieutenant Masterson player-model is apparently one of the last specimens created, who escaped and brought the army to take out Horzine. Turns out this was exactly what the Patriarch had expected him to do.
    • Some characters from the character packs are apparently former Horzine employees - Dr. Gary Glover, a scientist in a hazmat suit, is one of the last survivors of the team directly involved in the creation of the Specimens.
    • Rachel Clamely, the daughter of the Patriarch, was added with the Summer Event Update in 2014. Apparently the only surviving member of her family, she tries very hard to stop what her father has begun.
    • Captain Ash Harding's backstory. Rather than embrace being a Mafia Princess for a notorious crime boss, she chose to follow her dream of being a military officer and enlisted in the British Army.
  • Desperation Attack: A common tactic among doomed players is to throw all one's grenades at their feet when surrounded to kill as many Zeds with them as possible.
    • Can also be done unintentionally; as grenades, pipebombs and other explosives can easily kill the user (and in the case of the pipebombs, those can go off if the user shoots them).
    • Played with in the case of the Pipebomb Hat, where someone deploys one or more of the things in such a way that they are stuck to their own head. Since they are proximity-triggered, it works along the same line of thinking as throwing a pile of grenades at one's own feet. This is typically done against the Patriarch, who had to receive a cumulative resistance to pipebombs in an update. Amusingly, due to the lack of friendly fire under most circumstances, if you have someone else's pipebombs stuck to you rather than your own, you actually survive having them all go off right on your head with no damage.
    • Subverted with the Combat Medic after an update gave them grenades which release a gas that heals teammates and poisons zeds, so throwing your grenades at your feet when being swarmed will actually save you. Firebugs can do much the same when they got unique grenade effects as well, as incendiary grenades + immunity to fire = easy escape.
  • Diegetic Interface: The M7A3 assault rifle for the medic shows how many bullets are left in the magazine and how long you have to wait before firing a new healing dart via a small screen located below the sights. For added practicality, when your magazine is about to run dry, both the gun's ammo counter and the reflex sight turn red.
  • Ding Dong The Witch Is Dead: It is possible to kill the Patriarch while there are other specimens alive, in which case they just stop moving while the YOUR SQUAD SURVIVED text is displayed. What's more, any dead player respawns at this point as usual after a round ended, unlocking the associated achievement for surviving the map in question, even though they technically didn't, if they don't already have it.
  • Disaster Dominoes: DLC character Lance-Corporal Lee Baron was already in full EOD gear dealing with a bomb threat in downtown London when the Specimen attacks began. He learned that the best way to keep them at a distance was to blow them up.
  • Disc-One Nuke: Once you reach level 5 of any perk, you start to spawn with one of their weapons (or for Medic, his extremely tough body armor). Most of them can make the first wave extremely easy due to you normally being expected to take out the first wave with your 9mm and Knife. If you find some more weapons on the ground, selling them and your starting weapon can often let you get any weapon for your perk that you want by wave 2. Said weapons lying on the ground can also last you for a few waves if you get some ammo from the trader, or can save the entire game if a wave goes really bad. If you find yourself with almost no ammo and in an Everybody's Dead, Dave situation, finding a bullpup or a shotgun with a couple magazines worth of ammo can be all you need to turn things around and pull off a One-Man Army moment.
  • Double Entendre:
    • In the Abusement Park, there's machines hawking "Rainblow" condoms.
    • Hook-handed Circus Clots will occasionally say "Just let me stick the tip in".
  • Double Unlock: An example by default, as paid-for DLC weapons require that one-time payment of real money before you can buy them in-game with virtual dosh. You can use the weapons without buying the DLC, but that requires someone else who did buy the DLC to drop them for whatever reason.
  • Dual Boss: The Objective map Transit (which is the last map in the "story" and ties directly into Killing Floor 2) ends with a boss fight against two Patriarchs together, immediately after you learn the Patriarchs are all actually clones of the real one.
  • Dynamic Difficulty: Specimens grow in numbers as more players join. Most specimens also gain more health depending on the number of living players (particularly the Fleshpound and the Patriarch, which do this in lieu of spawning more often).
  • Eagleland Osmosis: Inverted. Suburbia, the first official map confirmed to be outside of the UK (it's in an American neighborhood), has British license plates on some cars and some other out-of-place stuff. This is due to reusing assets from other maps which, as mentioned, take place within the UK.
  • Emergency Weapon: Besides your starting nine-millimeter, you always have your knife. Its effectiveness is limited, but the "alt-fire" heavy blow can behead weaker enemies in a single stroke on most difficulties, and in the hands of a Berserker, it can be dangerous.
  • Enemy Chatter: Every enemy has a voice. Not always a clear one, but every enemy says something.
  • The Engineer:
  • Evil Laugh: "Hahahaha, FEAR ME!"
  • Exactly What It Says on the Tin: Suicidal mode. See also Harder Than Hard.
  • Excuse Plot: So there's a scientist who's mad with grief over the death of his son, and he's been hired to create an army of supersoldiers, but his project gets shut down, so he experiments on himself, and... ah, the hell with it. Guns good. Monsters bad. Apply the one to the other. Get money. Buy better guns. Kill the boss. Repeat from step one.
  • Expendable Clone: The original purpose of the experiments was to create an army of disposable clone soldiers.
    • It only gets freakier when you realize that some of them weren't actually made to be soldiers, such as the Scrake, the third strongest enemy, which was designed to be a medic.
  • Expy:
    • The Bloat is pretty much the Bloated Butcher from Blood, with a dash of exploding on death a la Left 4 Dead's Boomer.
    • Harold Lott is one to Harry Enfield's "Loadsamoney" sketch character.
    • Harchier Spebbington is both this to Indiana Jones and The Cameo from The Ball.
  • Flawed Prototype: All the specimens are failed attempts at creating supersoldiers.
  • Football Hooligans: Chopper Harris, a soccer enthusiast with a long police record of beatdowns taken and given. As far as he's concerned, the mutant apocalypse is just business as usual - only now he gets to use guns.
  • Four Eyes, Zero Soul: Dr. Kevin "The Patriarch" Clamely. It's more obvious on his loading screen artwork.
  • Fragile Speedster: The Crawler and Stalker are both fairly fast, but both have almost no health.
  • Freak Out: Mike Noble had one at a rave party after the specimens munched his girlfriend. He grabbed himself a katana and went to town.
  • Freudian Excuse: The only things Dr. Clamely cared about were work, and family. And then his son was shot through the head in a robbery... thus beginning his interest in "neurological redundancy".
  • Friendly Fireproof:
    • Friendly fire is off by default. It can be turned on, however, and your weapons are just as dangerous to teammates as to specimens.
    • Specimens can kill each other. There is an achievement to get the Bloat to do this. The Fleshpound can too, as it charges through its own in an attempt to kill its target.
    • Like Team Fortress 2, even without friendly fire players can easily kill themselves with explosives. To a lesser degree, fire-based weapons also hurt the user if used carelessly. Naturally, perks based around these weapon types take less damage from them, but a demolitions expert can still easily blow himself up by accident.
  • Full-Frontal Assault: The Scrake is the only fully dressed specimen.
    • The Clot, Crawler, Gorefast and Bloat are all bare-ass naked, though with no visible genitalia. A close look at the models shows that the dangly bits were surgically removed.
    • The Siren and Fleshpound are wearing nothing but a few restraints.
    • The Stalker, Husk and Patriarch are in their underwear.
      • When going through the game files and code, it comes to light that the Stalker was supposed to be naked. They were forced to wear black lingerie (indeed, one look at their in-game models makes it clear that their underwear texture was pasted on about 60 seconds before launch). Stalkers are indeed naked in the original mod, including Claire, a playable Stalker trained to join the good guys.

    G - N 
  • Game Mod:
    • Started out as one to Unreal Tournament 2004. Then the guys who did Red Orchestra (itself a Game Mod for the same title) were impressed and offered to make it a real game.
    • Later got one of its own, Defense Alliance 2.
    • Within the game itself, there are two levels for recognized mods - the first is stuff that is actually added to the game itself through patches, such as well-made maps. The second is a "whitelist" of custom maps and mods that can be used without disabling Perk progression.
  • Give Me a Sword: Don't have the dosh for a bigger gun? Ask your friend for the cash - or just ask them for the gun! Can be done literally by dropping a katana or claymore and letting another player pick it up. This can be extremely helpful for certain perks like the Sharpshooter, who don't really get access to a weapon that fires on full-auto (and can't just buy an assault rifle because most of the Commando's higher-level weaponry is prohibitively heavy and expensive). A higher-level Medic can pass off an MP7, an MP5M, or a Schniedzekk, all of which only weigh three blocks, to a Sharpshooter.
  • Gravity Screw: The Moonbase map, as would be expected. Sadly, third-party maps making use of similar low-gravity situations have yet to appear.
  • Guide Dang It!: Some weapons affiliated for a particuliar class can also be used by others and benefit from their perks: commandos can use the M4-M203 and keep the lower recoil, extended mags and better firepower, for example. Nothing ever tells you about it, except inspiration. And, if you don't think you can survive a wave as the weapons' intended perk, you'll have to buy them full-price.
  • Guilt-Based Gaming: When attempting to quit the game, it will note that "You can run. But they'll find you before dawn."
  • Guns Akimbo: You can buy two of any of the pistols, but it makes it harder to aim since when trying to look down your iron sights, you have to eyeball where the center of the screen is instead of just lining up the sights, and shots will deviate from that point when fired in this manner.
  • Hand Cannon: The Handcannon.
  • Half-Human Hybrid: Masterson is this. Thankfully, he's still willing to shoot Zeds in the face. This also goes for DLC character Security Officer Thorne, who is visibly mutated unlike Masterson. Apparently he underwent modification for the pay bonus. He seems to want to take a bite out of Dr. Glover.
  • Half the Man He Used to Be: The Hillbilly Crawler has nothing below the waist but its dangling spine. The Hillbilly Horror trailer shows he was working on a car and underneath it when it fell off its jack stands.
  • Hair-Trigger Temper: Unlike Scrakes, who may go berserk and quickly charge you when their health is damaged enough, Fleshpounds can do this from seeing you and your team long enough (though shooting them enough at once will piss em' off even faster unsurprisingly).
  • Harder Than Hard: In the first Christmas update, a difficulty above Suicidal was added, Hell on Earth.
  • Healing Shiv: The Field Medic's weapons are borderline examples. They are otherwise regular guns whose Secondary Fire mode launches a healing dart. Unlike the bullets, the darts are not hitscan and therefore it can be difficult to hit your teammates, especially when they're strafing and jumping around avoiding the Specimens. They're not "true" examples because the damaging and the healing parts are entirely separate functions (hitting a zed with a healing dart is as pointless as shooting a teammate with a bullet). He also has gas grenades as a more traditional example, as the gas in question hurts the Zeds but heals teammates.
  • Hitbox Dissonance: The hitboxes for the first game's Zeds are simply enormous.
    • According to the developers during TotalBiscuit's video, they were quite limited in that regard back then, also restricting the enemies to fairly stiff movement so that it wouldn't get worse for headshots. However, they claim to have improved them so much that its possible to accurately headshot a Stalker in the middle of doing a cartwheel in the sequel.
  • Hoist by His Own Petard: The Demolitions perk grants resistance to explosives in general, meaning that a high-level, armored Demolitions expert can survive a near-miss from a Patriarch rocket. However, when that same rocket sympathetically detonates all the pipebombs the Demolitions expert has carefully laid out to kill the Patriarch... not so much.
    • Same thing may happen when the Patriarch rushes into the minefield and the Demolition expert is standing too close.
    • Similarly, the Patriarch can hurt himself when trying to blow open a welded door with his rockets.
      • Until a patch removed the ability, it was possible to become sealed inside the Aperture vault with the door's welding percentage at 100% for the Patriarch wave. This led to the Patriarch repeatedly shooting rockets into the ultra-durable door, and eventually killing himself in the process. After the patch, he simply no longer attacks the door, and will instead walk around outside taunting you until you unweld the door yourself (the door also no longer respawns at 100% if destroyed).
    • This can happen to the entire team due to the Patriarch's randomized spawning locations. Dropping a bunch of pipe bombs to set a trap as he rounds the corner? Just make sure you're not near your own pipe bombs when he spawns in.
      • The Pipe Bomb Nerf made it so that they do not stack damage beyond a certain amount when placed atop/near each other anymore. This doesn't stop them from being awesome against the Patriarch, they must simply be spread out now. Someone did the math and figured out that 14 is the maximum before the decreasing return has each additional pipebomb contributing zero damage to his health. Unfortunately for the Patriarch, 14 pipebombs of explosives going off at once will deplete 51% of his health on even a full server on the hardest difficulty.
    • Low rank Firebugs often suffer from this as they ignite themselves with the blowback from using the flamethrower in close quarters. Averted once they level up enough to make themselves immune to fire.
  • Hold the Line: A common plan in most levels since the Welder allows you to funnel Zeds or hold them up by making doors impassable barricades that must be smashed down.
  • Holiday Mode: The Christmas event made all specimens Christmas-themed, such as Clots disguised as Santa Elves and Gorefasts made of gingerbread and exclaiming "Cholesterol doesn't kill people, I do!" There's also the appearance of three Santas - one playable, one replacing the Bloat, and the other replacing the Patriarch. However, the former appears to be a rather shoddy Mall Santa, the second seem to be clones of the real deal, and the last is a Killer Robot. All the above return for Twisted Christmas 2, which also features a new map, Ice Cave. And since Third time's a charm, the whole crew comes back for 2012... IN SPAAAAAAAAAAAAAAAAACE!!!
    • For Christmas 2013, no new christmas maps were added (we got Hell and Forgotten instead), but the themed specimens returned, allowing for a Christmas Husk (an animated snowman) to be walking around Hell...
  • Hollywood Silencer: Averted. The Firebug's MAC-10 has an attached suppressor, but its actual firing sound is rather distinct (when it was first added, it sounded like the AK47), and it has no effect on the AI since they always know where you are.
  • Hostile Show Takeover: GLaDOS got in contact with Horzine, it seems, providing some cloning vats for the Specimens. Then she decided to test them.
  • Hyperspace Arsenal: Excluding what you're currently using, none of your equipment - which in extreme cases can include three full-size shotguns or seven separate pistols, along with separate ammo caches for each - is ever visible on your character model. Anything that is can't be used.
  • I Know Mortal Kombat: Phil from the "Steampunk 2" character pack. From his bio: "...his so-called elite military training's come from endless hours playing every FPS spat out by the games industry and reading every gun nut magazine he could get his hands on."
  • Implacable Man:
    • The Fleshpound will not change targets unless it loses sight of whoever it was focused on. It will continue to chase and/or horribly mutilate its target through bullets, fire, chainsaws, rockets... and anyone unfortunate enough to be in its way, including other specimens.
    • Note that none of the specimens will actually run away, but most will actively change target or respond to damage.
    • On lower difficulties, a fully-leveled Medic or Berserker player counts as well.
  • Infernal Retaliation: Most of the stronger specimens have a lot more health than the Firebug's weapons of choice can chew through, requiring considerable time and ammo to put even one Scrake or Fleshpound down. And in the Scrake's case it'll be more likely to trip his charge threshold long before he burns to death. Some weapons have an easier time of it, though, such as the Trench Gun, which behaves like a flame shotgun and causes targets to burn to death even faster with repeated shots.
    • The player-usable version of the Husk fireball weapon can charge up a more potent blast, but without a low difficulty and a high perk level, a single fully-changed shot still won't be enough to put down Scrakes or Fleshpounds. A high-level Firebug, though, can stunlock Scrakes to death with repeated charged shots, and the repeated shots tend to make the Fleshpound rage in place or flail its arms around while on fire, giving time for even more shots.
  • Informed Ability: According to story, the Patriarch was nigh-unstoppable ("Armies fell before him, none seemed to be able to kill him, or even harm him"). In-game, a ragtag group of 6 armed only with various different small arms and maybe a rocket laucher and no armor support to speak of is able to take him down on their own.
  • "Instant Death" Radius: Do not melee a Fleshpound, and especially do not try to melee the Patriarch.
  • Instant-Win Condition:
    • When the Patriarch dies, all other Zeds immediately stop moving and attacking as the victory screen and score tally come up.
    • Averted in Objective mode. Once an objective is completed, all that changes is that enemies stop infinitely spawning - you still have to clear out any of them that are already there.
  • Interface Screw: Crawlers will blur and darken your vision if they hit you, Stalkers will paint your display blood red, Bloats will stick a gooey substance all over your screen, and Siren screams essentially give you heavy myopia while they last. Even getting bitten by a Clot disturbs your sight more than you might expect.
  • Intrepid Merchant: DLC character and Action Survivor Mr. Foster is apparently this, in a similar vein to the Trader herself. He also sung at "London's premiere karaoke bar" on the side. He was writing an autobiography and laments the deaths of England's publishers, as doubtless the chapter he is writing about his fight against the Specimens would have been a good read.
  • Invisible Wall: Often to keep you out of Specimen spawn points, but most of the official maps don't have too many. They instead tend to feature gravity barriers, in the form of ramps that the Specimens use to enter the area, but which the players are incapable of climbing over.
  • Jack of All Stats: The Commando has elements of this. He reloads any gun faster, can see enemy health and if they're cloaked, and can chain Zed Time extensions. He uses the general-purpose assault rifles and tears though the swarming smaller Specimens. He lacks heavy punch though, and is less effective than The Berserker, Demolitions or Support at taking out heavy Zeds. After enough practice as other Perks, and in higher difficulties, some players ignore the class entirely, as chaining Zed times can also be done by The Berserker, a decent Sharpshooter can pick targets off better with fewer shots, being able to see Specimens' health becomes a negligible ability when the Commando's best weapons merely chip away at their health, and seeing cloaked enemies can be emulated by setting them on fire.
    • The Support Specialist also counts in a sense, as he can carry more equipment than most, including extra grenades. However, his versatility depends on his gear, whereas the Commando has all his perks already available with the default pistol.
  • Jerkass: Martel Halliday, the Big Bad of Fright Yard's Objective Mode. He's the only NPC featured in Objective Mode to be openly hostile towards the players - Rachel Clamely had you wade through a horde of Specimens to try to stop them from getting to Paris; Ringmaster Lockheart had you wade through a horde of Specimens to save his own skin, but at least compensated you for it... Halliday has you wade through a horde of Specimens specifically to get you killed.
  • Katanas Are Just Better:
    • Fast and lethal, though not quite having the bite of the chainsaw.
    • Mike Noble has a preference for these, according to his bio.
  • Kill It with Fire:
    • The Firebug perk's job.
    • With the addition of the Flare Revolvers and the Trench Gun, everyone can get in on this, with the benefit of not setting themselves on fire as is wont to happen when using the flamethrower at close range. These other guns are also much lighter, and the Support Specialist's bonuses also apply to the Trench Gun, allowing him to either devastate up close or ignite at a distance in a wide arc.
  • Leeroy Jenkins:
    • Doing this is a good way to get killed. Unless you're a Berserker, in which case it's the whole point.
    • In his bio, Trooper Clive Jenkins is this.
    • As mentioned elsewhere, it is possible to attach proximity-triggered pipe bombs to your own head, especially useful for the Patriarch wave. Players using this tactic may typically shout the trope name or something similar as they charge toward their target.
  • Lightning Bruiser:
    • The enraged Fleshpounds and Scrakes with low health tend to charge the player at high speed and chainsaw them to bits.
    • The Patriarch, who gains an enormous boost in movement speed upon turning invisible and frequently uses this to charge towards players who can't see him and strike them with an outrageously powerful melee attack that kills unarmored players instantly on higher difficulties. The Patriarch actually teleports when invisible, proven by him bypassing welded doors entirely.
    • Patches turned every single Gorefast into one of these - despite their low health (relative to that of the others listed here), they can easily outrun the player and no longer have to stop moving to swing their arm blade. Multiple times.
    • The Berserker is second-fastest class in the game, enjoys a nice damage resistance, and deals out heavy damage with melee weapons. Also, an adventurous high-level medic is even faster, and with armor and the right hardware can dish out heavy damage.
  • Love Makes You Evil: The Patriarch views the specimens as his "children", and he gets pissed when you kill them, but the Sirens really take the cake; they're clones of his wife. Which he used to murder his real wife.
    • It goes deeper than that. The whole backstory kicks off when the soon-to-be-Big Bad misappropriates military funding to clone his dead son.
  • Luck-Based Mission: A few of the original Twisted Christmas achievements rely entirely on how generous the AI feels rather than any skill on the player's side. For example, one requires the player to kill three Bloats with a bullpup in one wave. With anything less than a full server, the game will barely spawn three Bloats per match if anyone tries to go for it.
    • Commando perk progression depends on Stalker kills with assault rifles, which pretty much only Commandos ever use. A lot of them, actually. The amount of Stalkers spawned per game varies wildly. Even if a lot spawn, its almost certain another class will kill them before you do. Although Commandos at least get to spot them more easily, but that won't help much when the Stalkers are taking point among a crowd of other specimens everyone is firing at. They are pretty frail, too.
    • A few Berserker-oriented achievements also rely more on luck than on skill, such as the one for chaining four Zed-time bonuses in a row (the game will wait until the last of a group to give you Zed-time for a kill) or the one for killing two Scrakes in one wave with the chainsaw (same issue as the Christmas Bloat achievement above).
      • Many, if not all, of the "Kill X number of Y Specimens with Z weapon" can be unlocked by using the Faked Players mutator, which is used in Solo play to simulate as many players' worth of Specimens as desired. Of course, you then must survive that many all by yourself instead of learning teamwork taking them all down. Since the mutator makes the game more difficult, it was eventually accepted and now Perk leveling can be done when using it.
    • The "Dignity for the Dead" achievement, for killing 10 Zeds who are feeding on dead teammates' corpses, depends on A) anybody on your team actually dying, B) the enemies who do him in actually bothering to chomp on his corpse instead of just immediately going for you next, and C) the game actually deciding to credit you with killing the Specimens mid-feed (the game has/had a notorious record for not tracking certain achievements' progress 100% of the time).
  • Machete Mayhem: One of the Berserkers weapons, it's a step up above the knife, only takes up 1 block of weight and can be found around any map. Plus it sells well.
  • Mad Doctor: The Patriarch. According to the ModDB entry, he became obsessed with his work.
    • The Summer Sideshow event mentions that Kevin Clamely had an equally-insane great grandpa named Errol Clamely, and that either him or young Kevin were responsible for the Zed freakshow.
  • Made of Iron: Most of the bigger, badder specimens can take stupidly large amounts of punishment, but the Siren in particular is odd - while she can't take as much as Scrakes or Fleshpounds, one would think an anorexic-looking crazed girl in a straitjacket would have less health.
    • Even odder, she's got a Hard Head! Most specimens' heads will always explode if half their total health bar is dealt to their head - the exceptions are the Scrake and the Siren, whose heads only explode if 65% to 66% of their total health is dealt to their head (not including the Patriarch, whose head simply doesn't explode).
  • Made of Explodium: The Bloat usually explodes when killed. Many parallels are drawn to the Boomer.
    • Although he's more like the Spitter, using acid rather than an otherwise harmless liquid that attracts more enemies.
  • Made of Plasticine:
    • Clots, Crawlers and Stalkers have little to no health, and most specimens lose limbs very easily. Players also tend to take lots of damage, but you do have the ability to heal yourself and each other.
    • Zed time seems to make heads popping or limbs detaching more spectacular.
  • Make Me Wanna Shout: The Siren attacks via a horrid scream.
  • Meatgrinder Surgery: Implied. According to its bio, the Scrake was designed as a medic. So why is it carrying a chainsaw?
  • The Medic:
    • The Field Medic perk makes you this, of course.
    • Alfred Anderson is this in his bio, he was a paramedic at a London hospital.
  • Monster Clown: What the Bloat and Fleshpound were reskinned as for the Summer Sideshow event.
  • More Dakka: The Medic's SMGs boast the highest fire rate out of all weapons in the game (but mediocre overall DPS). Bonus points go to the Schneidzekk, which will empty a full magazine in 3 seconds, stat. On the plus side, if you aim for the head, only a Scrake, Fleshpound or the Patriarch will survive the bullet rain, but will be seriously hurting, in the case of the first two. Since the Medic can carry up to three of the four available mediguns at once, it's possible for a high-level Medic to finish off Scrakes and Fleshpounds by running through one gun after another, and their improved armor makes them better able to survive pulling this stunt (though this becomes more risky the higher the difficulty).
    • And for a non-combat occurance of this trope, the healing darts on the Medic's weapons each have their own separate recharge pools. At high levels, they all recharge just fast enough that a Medic carrying three of said weapons will be able to fire a dart again by the time they cycle back to the first weapon. For this reason and a few others, the M7A3 is typically the one not chosen out of the four, because it's a slot four weapon and the others are all on slot three, making it easy for a Medic player to spam healing darts without end.
  • Mythology Gag: Some assets are lifted from Red Orchestra and placed on quite a lot of maps, with KF-Farm being the most notable example as a full level that got carried over from the base game with some alterations. As such, many props from World War II can be spotted in modern-looking levels as well.
  • Nail 'Em: The Hillbilly Horror Event added Vlad the Impaler (also known as the Vlad 9000), a magazine-fed nail shotgun for the support specialist. The nails can ricochet and hit other specimens, which makes up for the terrible range. Halloween 2013 also added the Seal Squeal Harpoon Gun, which appears to be a large industrial rivet gun modified to fire explosive-rigged harpoons.
  • Never Split the Party: While not as bad as some other games, going off by yourself is a good way to get mobbed and therefore killed. In addition, it's extremely difficult to kill even a single Fleshpound or (after patches) Scrake without serious injury or deathnote . It doesn't help that the toughness of the monsters/their numbers increase at a far faster rate than the raw strength of your party, and using your healing syringe on yourself is only half as effective as healing teammates.
  • Night of the Living Mooks: The entire game, pretty much. Although they're not technically undead.
  • No Celebrities Were Harmed: Martel Halliday (the Mission Control NPC in the Fright Yard map) looks almost exactly like Colonel Sanders, down to the distinctive leaning-on-cane pose on his portrait. He also speaks with an obvious accent.
  • No Fair Cheating: Perks are disabled and unable to be leveled up if a game has any mutator that only spawns low-level mooks or otherwise makes the game easier enabled.
    • If, however, you decide to add a mutator that makes gameplay more difficult, it will likely still count toward your progress. This was the case with the Faked Players mutator, which allowed for six or more survivors' worth of specimens to spawn in offline single player matches. If you decide to try this, hope you like running around in circles shooting behind you!
  • No Hero Discount: Logically, the Trader's life should depend on you killing the hordes of bloodthirsty specimens overrunning the area. Apparently that isn't quite enough to warrant a discount. Subverted in that you do get discounts for certain weapons depending on your chosen perk and its level.
  • Not Using the "Z" Word: They're "Specimens." Justified in that they're not undead or plague-bearing or even necromancy products, they're military clones turned into brain-dead cannibals. Funny enough, the official nickname for the Specimens is a Zed. Absolutely no one calls them that, in-game or out, but two guns are named for getting rid of them: the Zed Eradication Devices, see Recursive Acronym.
    • The player characters refer to them as zombies on occasion. Granted, it's always to call them inferior to zombies.
      Insult Specimens: "You're too soft to be a zombie!"
    • Zed (Zee in North America, where "Ƶ" may be taken as Zed) is simply the first letter in the word Zombie, which more an abbreviation than a name. They are officially called specimens. All three terms are correct parlance in the community.
    • In some localizations, Clots are called zombies by the game itself though.

    O - Z 
  • Offscreen Teleportation: The spawn points of Specimens are basically wherever a player isn't looking. Even directly around the corner behind you.
  • Off with His Head!: All the specimens are recipients of an experimental process that enables them to survive absurd/fatal levels of nervous damage and keep on trucking, in addition to other unique survival mechanisms. It turns out that for all the genius engineering, military hardware and bladed implements can still liberate them of their heads, and while they usually don't immediately die from that, they still bleed to death within a few seconds.
  • Oh, Crap!:
    • Essentially the reaction whenever the Patriarch spawns in the opposite direction from where the players set up their wall of pipe bombs. Doubly so if he spawns in the middle of the group. It does happen sometimes.
    • There's a voice command specifically aimed at vocalizing this sort of reaction. "We're screwed! Leg it!" "Oh crap, run!"
  • One Bullet Clips: Played straight, though the HUD only shows the number of magazines you could fill with the number of bullets you have. This excludes the pump-action and double-barrel shotguns, the lever-action rifle, and the crossbow, which load one round at a time. Oddly enough, you can't reload the double-barrel shotgun after firing only one barrel.
  • One-Steve Limit: Averted, there are three Harolds: Harold Hunt, the Steampunk support specialist, and the Harry Enfield Captain Ersatz. There's also two Daves, the Steampunk medic and Dave "The Butcher" Roberts. Tripwire seems to have caught onto this, as Doctor Dave is now Doctor David.
  • Our Clones Are Different: The Clots are failed clones of the dead son of the man who invented the process under contract by the UK government for Super-Soldier research. They're grown through a combination of a biomechanical "Mother Clot," which both renders down bodies into a mass of cells and then "builds" a new body out of them, and a transgenic virus that over-writes their DNA with that of the dead man's. However, being Born as an Adult without a corresponding lifetime of experience and socialization (and perhaps some undiagnosed mental sickness or another that he was genetically pre-disposed to) results in a person with the mentality of an angry gorilla and the body of a fully-grown man in the prime of his life. Since they still have the virus in their bodies, clots are essentially Plague Zombies as well (though it's not much reflected in the gameplay proper).
  • Our Zombies Are Different: Instead of the living dead, they're clones meant as military cannon fodder Gone Horribly Wrong.
  • Poison Is Corrosive: Bloat acid is marked as poisonous by the game tips. However if you're killed by being puked on, the death message reads: "X was corroded by Bloat acid".
  • Police Brutality: Constable Briar apparently has a history as a riot cop of "bludgeoning hippies" and "manhandling environmentalists." Such tendencies serve him well against the Specimens.
  • Powered Armor: Horzine Industries was apparently publicly developing a next-generation suit of combat armor simultaneously to the Specimens. Agent Wilkes, DLC character and British Overt Operative wears it, having secured it from their labs (though it offers no in-game benefit). According to his bio, Horzine was great at multitasking both horrifying undead abominations and making great armor Security Officer Thorne also wears what looks to be the same armor minus the helmet and most of the arms.
  • Power Limiter: That...glowy thing...on the Flesh Pound's chest is constantly pumping it full of depressants, sedatives, tranquilizers and the like. However, if the apparatus senses from its vitals that the specimen is in danger (normally from itself and its own temper), it'll stop with the downers and start pumping it full of adrenaline and stimulants.
  • Pre-Mortem One-Liner: Courtesy of the Patriarch.
    • "One in the pipe!"
    • "Wait right there, I'll make this quick!"
    • The Robot Santa version gets a few new such lines - "And not a creature was stirring, because they're all dead! Ahahaha- eh, ho ho ho ho ho!"
  • Pun: A few of the achievements come to mind:
    • Random AXE of Kindness. Kill 15 enemies with the Fire Axe in a single wave.
    • The L.A.W. That Broke The Camel's Back. Deliver the Killing Blow to the Patriarch with a L.A.W. Rocket.
    • Quite a few of the Circus Patriarch's lines, too. "Ladies and gentlemen, we hope you enjoyed the show as much as we did! You might say... it was to die for." "It's time to knock 'em dead!" "Enough clowning around!"
    • The Circus Husk's lines are full of bad puns. "Fire is the hottest new item of the season." "Please remember that there is to be no smoking while the show is in progress."
    • Some of the Circus Scrake's lines, too. "What manner of monkey business is this?" "This shit is bananas!"
  • Ragtag Bunch of Misfits: The player characters include, among others, a day trader and his girlfriend, a football hooligan, a raver, a failed mall Santa and an obnoxious wealthy guy based on Harry Enfield's "Loadsamoney" sketch character.
  • Real Is Brown: There are shades of brown basically everywhere in a map. Some custom maps made official through patches are more colorful, though.
  • Recoil Boost: The low gravity of the Moonbase map allows for weapons with enough recoil, primarily shotguns, to throw players about if they fire them in the air. Extremely useful for quick escapes, as no Specimens can match the speed you gain in this manner. Too bad Sirens can still get you with their screams and Crawlers will take advantage of zero gravity too.
  • Recursive Acronym: The Zed Eradication Device, also known as the Z.E.D.
  • Recycled In Space: The 2012 Christmas event adds a map located on the moon, complete with low gravity.
  • Replacement Goldfish: Several million inhumanly tough deformed murderous goldfish.
  • Revolvers Are Just Better: Twisted Christmas 2 brings a .44 Magnum revolver for the Sharpshooter. The Weapon Community Pack DLC adds the Flare Revolver for Firebugs. Like the other pistols, they can be dual-wielded and are very effective for the "hit and run" strategy.
  • Revive Kills Zombie: The Combat Medic's grenades release healing gas that can also harm the Specimens.
  • Reward from Nowhere: You earn dosh by killing Zeds. Where it actually comes from is a secret to everybody.
    • All things considered, judging from how it jumps up if you survive the wave, it may be a credit the merchant is giving you. The actual thrown money is probably just a graphic representation of donating funds to friends.
  • Set a Mook to Kill a Mook:
    • Very possible with Bloat bile, which tends to provoke bigger Specimens into attaking Bloats. One of DLC's guns is a modified leaf blower which allows you to shoot streams of Bloat bile straight at monsters and potentially turn them against each other.
    • Letting an enraged Fleshpound plow through a swarm of other Specimens is a good way to have him earn the wrath of whoever survived the charge; most of the time it's Scrakes who will eagerly turn on him.
  • Sexy Santa Dress: During the holiday events, the Stalker wears a very skimpy Santa Costume.
  • Sequel Hook: The Transit - Objective Mode, added with the End Of The Line - Summer Event Update in July 2014, serves as a bridge between the original game and its sequel.
  • Short-Range Shotgun: Mostly averted - the hunting shotgun, in Doom Super Shotgun fashion, is too inaccurate to use past close range, but every other shotgun is still effective up to medium range. Strangely, the AA12 is actually more effective at longer ranges, due to the smaller number of pellets per shell.
    • The Hillbilly Horror Event for Killing Floor added Vlad the Impaler, a nail shotgun. It has acceptable range and awkward spread, but the nails ricochet quite a bit. And it has a flashlight.
    • The Trench Gun includes the ability to set Zeds on fire, whether a Firebug pulls the trigger or not. This makes it useful both up close and relatively far away, as up close targets receive heavy damage from the blast, while further/multiple targets are set on fire and take more damage trying to get closer.
  • Smurfette Principle: While the Trader does play an important role in Killing Floor, Ash Harding, Mrs Foster, Steampunk Mrs Foster and Dr. Rachel Clamely are the only playable female characters. They snark, swear, and blow stuff up just as much as the male characters do.
    • The number of total women is increased to seven when including the Stalker and Siren Specimens. The Crawler's gender is dubious — it's reskinned as a female Siamese Twin during the Summer Event, but during the Hillbilly Halloween and Twisted Christmas event, it's a male hillbilly with a severed torso and a male reindeer, respectively. The same thing applies to the Bloat, who is reskinned as a big obese woman during the Hillbilly Halloween, but has male variations in other events.
  • Snake Oil Salesman: The Mechanical Man (Summer Sideshow version of the Husk) is a robotic version of this trope. His product is fire.
  • Sniper Pistol: The first shot is pinpoint accurate for most weapons, notably with the handguns. Even when dual wielding! That said, you get no crosshair, and bringing up the iron sights with the right mouse button reduces your walking speed. In the hands of a sharpshooter, though, it's absolutely lethal. On lower difficulty levels, even the starting handgun a perfectly usable weapon even late in the game, allowing skilled players to rack up headshot after headshot.
  • Sociopathic Hero: Several characters seem to be this, according to their bios. Joining their number is Kerry Fitzpatrick, an escaped psych-ward prisoner who put the hurt on the specimens after they put the hurt on his guards. He's probably stretching the "hero" part.
  • Sole Survivor:
    • Private Schnieder's squad was wiped out shortly after they were deployed. He had two options. Die alone, or shoot, stab and bludgeon his way to survival. Guess which one he picked.
    • Captain Ash Harding is the only one left from her command and she's pissed that her men died.
  • So Long, and Thanks for All the Gear: If a player leaves mid-game, all the money they had, along with all their weapons other than what they had equipped at the time, disappears with them. Nicer players tend to at least donate their best gun to a teammate before they leave, though no such luck if their connection gives out unexpectedly.
  • Soundtrack Dissonance: The Christmas event map "Santa's Evil Lair" has you killing Zeds while the music from The Nutcracker plays in the background.
  • Steampunk:
  • Stuff Blowing Up: Leave this to the L.A.W. and the plentiful grenades, or the Demolitions Perk and its two dedicated grenade launchers, plus an underbarrel one on the new M4 Carbine.
    • And now that Halloween 2013 has rolled around, there's an exploding harpoon gun and a six-barreled rapid-fire lock-on mini-missile launcher to play with.
  • Suicide Attack: Even with the pipe bombs' nerfing, it is still a viable option to attach several to your head for the Patriarch wave (unless you're playing Solo); pipe hats can still remove over half of the Patriarch's health on the hardest difficulty on a full server (assuming you're wearing 14 or more of them!), but given enough time beforehand, it would be better placing said pipes in strategic places and getting the Patriarch to run over them during the upcoming fight.
  • Survival Horror: The game bills itself as "co-op survival horror" and the monsters are scary enough, but the plentiful ammo, health, and levity keeps the proceedings from getting too frightening. Unless you are playing on the higher difficulties or course.
  • Take That!:
    • One of the Taunt Button insults is "You're pathetic! Like a bunch of bloody Millwall fans!"
    • Twisted Christmas 2 adds, along with two versions of the American M4A1 carbine, an achievement titled "Bloody Yanks" for expending an entire magazine but only killing a single specimen with it.
    • One of the insults towards other players is "Wayne Rooney is smarter than you!"note 
  • Taking You with Me: In dire situations, you can throw all your grenades at your feet when surrounded to kill as many Zeds with you as possible.
  • Tactical Rock–Paper–Scissors: Because of resistances some Zeds have to certain weapons, it becomes really important in higher difficulties. Basically boils down to: explosives beat Fleshpound, melee beats Scrake, assault rifles beat Crawlers and Stalkersnote , headshots beat Bloats, and fire beats Scrakes, Gorefasts and Sirensnote .
  • Taunt Button: With just a few short keypresses, you can insult your opposition ("You couldn't scare my mum!")... or your allies. ("I've met smarter donkeys than you lot!")
  • Title Drop: Descriptions for community-made maps tend to shoehorn these in, regardless of whether the resulting phrase makes any sense with context or not.
  • Took a Level in Badass: Pretty much par for the course for the survivors, especially for all the Action Survivor types.
  • Turns Red:
    • The Flesh Pound literally turns red when he enters attack mode thanks to a glowing battery implanted in his torso.
    • The Patriarch has a red shimmer when entering his invisible fleeing/attacking mode.
    • The Commando can see the otherwise invisible Stalkers who are colored in a red-tinted pattern.
  • Unstable Equilibrium: The Demolitions class as a whole. Players are usually short on cash, and the Demo's weapons are fairly pricey even at discount. Discounts that are harder to earn than those of other perks because of the price barrier. Choosing when to convert from your current class to a Demolitions - by virtue of selling your weapons - is a tough strategic decision, and that's assuming no one else did already. Each shot should be carefully assessed, as it is very easy to go overboard and waste explosives. With a grenade launcher on your hands, though, you can clear crowds in the blink of an eye and deal with the dreaded Fleshpound, who is weak to explosives. A Demolitions has only two Achilles Heels: Scrakes, and his own explosives.
  • Unbreakable Weapons: Every Berserker weapon other than the Buzzsaw Bow has unlimited use, making them potentially very cost effective if you kill enough enemies with one.
  • Unexpectedly Realistic Gameplay:
    • While leveling the Firebug to the max level, the player will grow much more resistant to fire damage until, and when they reach level 6, they will be completely immune. Does the same thing work with the Demolition perk? Nope! While the player does toughen up to the self-splash damage from explosives, it does not make them immune (and it's fairly easy to die to one's own explosives even on level 6). This makes sense, since while it's possible to make one's suit fire-proof, explosion-proof suit is a different story entirely.
    • Having an armor vest saves a lot of trouble, especially on higher difficulties, but even armor suit won't protect you from fall damage (because armor vest makes no difference when one falls to the ground from a great height) and Siren screams (which go straight for the head and thus ignore any armor points still left).
    • Shooting a grenade (or even hitting it with splash damage) that had been just discharged will make it explode prematurely. While it can be fun to perform certain feats against the specimen, you can still harm yourself by hitting your own grenade with a stream of fire or even a flare gun.
  • Unusable Enemy Equipment: Understandable, given that the few specimens who have weapons have them grafted on. This did not stop the Husk's Fireball gun from becoming a usable weapon, as of Twisted Christmas 2. You still can't take it from a dead Husk though; justified as the version he uses is, as mentioned, grafted to its arm, while the player version is modified with a grip.
  • Violation of Common Sense:
    • Confronted by a giant cannibalistic super soldier with a chainsaw for a hand? The best course of action is to engage it in hand-to-hand combat, which stunlocks it with each hit, even past the point where it normally becomes enraged and impossible to stun. This one is so bad that most players are unaware of it, and playing on public servers is more likely to end with the Berserker dead as clueless teammates "help" by just shooting the Scrake on sight, making it ignore the Berserker's stunlocking effect and promptly disembowel them.
    • Strapping several proximity bombs to your face is also surprisingly effective, especially if friendly fire is off.
  • Visible Invisibility: Stalkers have a shadow, even when they're cloaked. Alternatively, if you're a Commando, they appear as a bright red form when they get within a certain distance.
  • Wake-Up Call Boss:
    • Most new players underestimate the Fleshpound.
    • What happens the first time you fight the Patriarch - up till now, you've only been worried about melee (barring the odd Husk fireball) and can outrun everything. Suddenly you're up against an 8 foot monster with a combined minigun-rocket launcher for a left arm that can turn invisible, run twice as fast as you, smash you across the room in melee, take multiple anti-armour rockets to the face without dying, summon more specimens and heal himself.
  • White Gangbangers: Kevo the Chav, a slacker who spent most of his time drinking cheap lager and trying to work up the stones to shoplift. He was as surprised as anyone else when he found himself fighting a tide of angry mutants - and surviving.
  • Yandere: Doctor Jeffery Tamm was a Type 1 to his college crush and even helped build and program a robot to take her place.
  • You All Look Familiar: The specimens. Hand Waved with cloning.
  • Your Head A-Splode: What happens if a Siren kills a player with her scream.
  • Zombie Apocalypse: Although they're not actually zombies (more like military clones, called "specimens" or Zeds), this is pretty much the plot of the game in a nutshell.
  • Zombie Gait: How Clots and Bloats move around. Gorefasts too, until they get close.

"I'm cutting this one open, lads!"

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