[[quoteright:256:http://static.tvtropes.org/pmwiki/pub/images/Killing_Floor_Logo_3698.png]]
[[caption-width-right:256:Just maiming and injuring can also occur, however.]]
->''"On the [[NextSundayAD last day of August]], London turned into a [[TitleDrop Killing Floor]]."''

->''"I told you, I am welding this [[BritishAccents doah]]!"''

A cooperative online ZombieApocalypse FirstPersonShooter for PC published by Tripwire Interactive on the VideoGame/{{Unreal}} [[GameEngine Engine 2]]. Originally a mod for ''VideoGame/UnrealTournament2004'', 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 [[RagtagBunchOfMisfits a bunch of surviving military, police personnel, street thugs,]] [[VideoGame/TeamFortress2 the Pyro]], [[RagtagBunchOfMisfits a Queen's Guard, and more]] sent into various areas to wipe out the [[NotUsingTheZWord Specimens]] of a FreakLabAccident GoneHorriblyWrong. 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 [[FinalBoss Patriarch]], the creator of all the specimens, who has become a genetic monstrosity himself, happens. [[ExcusePlot The game's story is not exactly a masterpiece]], but it has [[KillEmAll an obvious goal]].

If the basic premise sounds like [[VideoGame/Left4Dead anything familiar]], it's totally different. (Mainly because the original ''Killing Floor'' mod came out first.)

A top-down shooter spinoff of the game titled ''Killing Floor: Calamity'' has been confirmed for OUYA; it was released on December 18th, 2013. And on May 8th 2014, PCGamer announced [[http://www.pcgamer.com/2014/05/08/killing-floor-2-exclusive-first-look-co-op-fps-horror-with-the-most-advanced-gore-system-ever/2/ a sequel is in the works.]]

Has a modest [[ShoutOut/KillingFloor Shout Out]] page.
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!!Tropes that appear in Killing Floor include:
* AbnormalAmmo: 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.
* ActuallyADoombot: Transit (Objective Mode) confirms without a shadow of a doubt that Patriarch has been cloning himself as well.
* AllThereInTheManual: The entire plot, centering around a [[OmnidisciplinaryScientist 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.
* AlternateRealityGame: Is one of the 13 indie games that formed the bulk of the material of Creator/{{Valve|Software}}'s "[[http://valvearg.com/wiki/Valve_ARG_Wiki PotatoFoolsDay]]" ''VideoGame/{{Portal 2}}'' ARG.
* AKA47: 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). Also, similar to ''VideoGame/Left4Dead2'', the game's "[=AK47=]" is actually a [[http://www.ak-47.us/Article_Detail.php?g=content1219989594 Draco AK-pistol]], modified with an unused AIMS-style folding stock. Of note is [[http://cdn4.steampowered.com/v/gfx/apps/210944/ss_49159dcb487ab3c267cc8c1c01239f82df7a250d.1920x1080.jpg?t=1372871611 the promotional image]] for the [[BlingBlingBang Golden Handcannon(s)]], which refers to it/them by the Desert Eagle name.
* AmusementParkOfDoom: The summer Abusement Park map, complete with freakshow skins for the Zeds and CreepyCircusMusic.
** And with the next two Summer Sideshows events we now have Hellride and the SteamPunk themed Steamland maps.
* AnAxeToGrind: One of the melee weapons is a fireaxe. Following the Twisted Christmas Event, completing an achievement in another game unlocks a [[UpToEleven dwarven battle axe]].
* ApocalypticLog: 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 HoldTheLine. Others mention the aftermath of your team's helicopter going down in an infested area, with specimens closing in on you.
* ArmCannon: 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!
* ArmorIsUseless: GameplayAndStorySegregation in the opposite sense - a few characters are wearing heavy gear/armor that does nothing useful (the description for Lee Baron [[LampshadeHanging specifically mentions]] that specimen claws and teeth tear right through his EOD gear), but in-game body armor is almost necessary to survive.
* ArtifactMook:
** 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 it 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.
* ArtificialBrilliance: 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 ArtificialStupidity, 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.
* ArtificialStupidity: 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.
* AscendedFanfic: Numerous well-made custom maps and at least one pack of custom weapons have been officially added to the game through patches.
* AscendedMeme: 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 other character DLC which are $2 for a pack of 4.
* AxCrazy: 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 [[GoodFeelsGood and would feel good while healing people]], but found that braining blokes [[EvilFeelsGood felt even better.]]
* AwesomeButImpractical: The Berserker perk can turn into this in later waves or later difficulties - being up close and personal with that many enemies, in particular that many Fleshpouds and Sirens, gets you killed very quickly.
** On the other hand, expert Berserker players can easily run circles around most Zeds, and survive without any backup even on the highest difficulties.
*** Being able to stun many specimens with melee attacks definitely helps... unless your teammates interrupt the effect with their firearms.
*** Unfortunately, the Berserker also has the side-effect of blocking the lines of fire for the other players.
** Going GunsAkimbo often has this effect, in that you have to sacrifice precise aiming for doubled firing rate and ammo capacity.
*** It does not get in the way, however, if you just [[Film/{{Aliens}} keep them handy for close encounters.]] Bullet-spam, aiming or not, with dual pistols is a decent way to get you out of a jam.
** 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 DifficultButAwesome by a skilled player, particularly a Sharpshooter that wants some full-auto teeth. Careful trigger discipline can compensate somewhat for the [[MoreDakka absolutely absurd fire rate]] and BoomHeadshot 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. 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, compared to the other weapons' more open sights. It also goes for a hefty price even when well-leveled.
** 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, 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 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 ''6250'' to fill up - but only holds 30 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. It's only useful against the Patriarch - money serves no purpose after the wave, and a capable sharpshooter can take out the rest of the specimens in that wave with their 9mm.
* BadassMustache: The Patriarch sports one of these in his default model.
* BadassNormal: It'd be easier to list who isn't one.
** The default player characters are two regular cops and four regular soldiers.
** [[TheEngineer Foundry Worker Aldridge]], who was rudely interrupted during his lunch break.
** DJ Scully, [[DangerousDeserter an AWOL soldier]] [[HeelFaceTurn turned DJ]] [[TheCallKnowsWhereYouLive forced back on the battlefield, after Zeds slaughtered his party-goers.]]
** [[BadassInANiceSuit Mr. Foster,]] a day trader who was working on an autobiography before the outbreak.
** [[MadScientist Dr. Gary Glover]], a scientist involved in the Specimen's creation [[TheAtoner who wants to set things right]].
** Mike Noble, who [[LetsGetDangerous tapped into his homicidal side]] at a rave GoneHorriblyWrong.
** [[PunkRock Harold Hunt, the frontman for underground punk band "The Fecking Nancies".]]
** [[TheSociopath Kerry Fitzpatrick,]] an AxCrazy escaped convict being transferred to a psych ward.
** [[CombatMedic Paramedic Alfred Anderson]], who was working night shift at the time of the outbreak.
** [[ThrowDownTheBomblet Lance Corporal Lee Baron]], who was investigating (and defusing) a bomb threat during the outbreak.
** [[FootballHooligans Chopper Harris]], who was now free to beat on people with no consequences.
** [[PrettyFlyForAWhiteGuy Kevo the Chav]], wanna-be thug who grew a pair in time for the apocalypse.
** [[BadassPreacher Reverend Alberts]], who wasn't expecting to have to apply his knowledge of horror films.
** [[BadassSanta Bill "Baddest Santa" Weeks]], a MallSanta who got fired and is taking it out on the specimens.
** [[RedOrchestra George and Nikolai]], a couple of WW2 WarReenactors.
** [[TheMafia Dave]] "TheButcher" [[TheMafia Roberts, a banker turned mob enforcer]] who's been tasked by TheDon with cleaning up the streets.
** [[MadScientist Dr. Jeffery Tamm]], [[SmartPeopleBuildRobots a robotics expert]] [[DefectorFromDecadence at Horzine]] who is attempting to [[RoboticSpouse recreate his college crush.]]
** [[AwesomeMcCoolname Samuel Avalon]], a [[FiremenAreHot photogenic]] [[EmergencyServices fireman]] with [[SociopathicHero a violent dark streak.]]
** [[McNinja Rob Allan, alias Shadow Ferret]], a wannabe [[HighlyVisibleNinja urban ninja]] with aspirations at being a VigilanteMan.
** [[EccentricMillionaire Harold Lott]], the youngest (and surprisingly wise about it) winner of the british lottery, who started to kill Zeds a bit [[PatrioticFervor to save London]] and mostly because [[MoneyDearBoy his battles are displayed live on one of his pay-per-view cable channels.]]
** [[TheLadette Captain Ash Harding]], a MafiaPrincess who became a soldier instead of a mobster and has a score to settle with the Specimens for exterminating her whole unit.
* BadSanta: The Christmas-themed Bloats and Patriarch.
* BeatThemAtTheirOwnGame: Two achievements related to [[KillItWithFire 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 [[ChainsawGood chainsaw]], their signature weapon, in one wave.
* BerserkButton:
** 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. [[http://www.youtube.com/watch?v=wSTxDHyqoXY 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 [[GoodBadBug 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.
* TheBerserker: [[ExactlyWhatItSaysOnTheTin 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 [[MacheteMayhem 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 [[AnAxeToGrind fire axe]], [[KatanasAreJustBetter katana]], or [[CoolSword claymore]], or become the world's most painful doorstop with a bloody awesome [[ChainsawGood 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}} Big Sodding Gun]]: Usually said while equipping one of the heavy weapons like the LAW and the M99, but as of the 2012 Winter Event, 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.
* BigDamnHeroes: Can happen to you, or anyone for that matter.
* BlackComedy: Pukey the Clown is a fan of this, usually laced with DeadBabyComedy.
* BladeBelowTheShoulder: The Gorefast. The Scrake too, but [[ChainsawGood with a chainsaw.]]
* BlingBlingBang: 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.
* BodyArmorAsHitPoints: 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 exceptions[[note]]Fire damage from Husks (armor protects from 99% of the damage), Bloat vomit and walking into ambient fires (armor stops health damage entirely), and Siren screams ([[ArmorPiercingAttack armor is ignored entirely]])[[/note]].
* BodyHorror: 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. [[ArsonMurderAndJaywalking And has a pornstache.]]
* BoomHeadshot: 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.
* BoringButPractical: 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.
** 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 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.
* BossBanter: The Patriarch has a rather large list of lines. "Excellent, another batch of subjects!"
* BottomlessMagazines: 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 40[[note]]the reasoning for this may cross over with TheArtifact - the bonus originally only applied for this one gun, which does have both 20- and 40-round magazines in real life, so when they started adding more Medic weapons it got a little out of hand[[/note]], 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).
* BreakoutCharacter: For a game with an AllThereInTheManual 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. [[http://www.youtube.com/watch?v=ioENl5cJXwo#t=1m7s Everyone]]
* BreakOutTheMuseumPiece: The Halloween 2012 event adds a bunch of UsefulNotes/WorldWarI and UsefulNotes/WorldWarII-era weapons, including an [[RareGuns MKb42]], [[CoolGuns/SubmachineGuns M1A1 Thompson]], and [[CoolGuns/{{Shotguns}} M1897 Trench Gun]] [[IncendiaryExponent loaded with incendiary buckshot]]. Owning the stand-alone ''VideoGame/RedOrchestra'' 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 [[CoolGuns/{{Rifles}} scoped Lee-Enfield]].
* BritishAccents: Taken to hilarious levels. Justified because it takes place in the U.K. and the voice actors (who are obviously both British themselves) are one of the developers and a retired bobby cop.
* BritishRoyalGuards: Captain Sir Richard Wiggins, [[BlueBlood a minor aristocrat]] with a commission in the royal guards. He sees specimen hunting as [[BloodyHilarious jolly-good fun.]] His outfit consists of his roughed-up and [[FashionableAsymmetry missing-a-sleeve]] red coat and fuzzy hat, with some pouches and holsters tacked on.
* BulletTime: 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.
* ButtMonkey: 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. [[BloodKnight All hail the end of the world.]]
* CallingYourAttacks: Played straight with the Patriarch, who utters distinct lines before his [[PreMortemOneLiner rocket or gatling gun attacks]]. Subverted when he turns invisible, charges, and without so much as a word punches a {{Combat Tentacle|s}} 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.
* TheCameo: The RED and BLU Pyros from ''VideoGame/TeamFortress2'' appear as selectable character skins. See {{Crossover}}.
* CameraScrew: When the Patriach first spawns there are about five seconds during which you are forced into a third-person view of him as he stands up and gets ready to fight. If he spawns near you, [[GameBreakingBug the camera continues viewing the Patriarch]], during which you can't see well enough to do anything while he can do [[GatlingGood whatever]] [[CombatTentacles the hell]] [[StuffBlowingUp he wants]] to you.
* ChainsawGood: Go ahead and guess what one of the best melee weapons is. The Scrake also has a chainsaw ''for an arm.''
* CharacterClassSystem: 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:
** TheBerserker: 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.
** [[JackOfAllStats 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.
** [[ShotgunsAreJustBetter The Support Specialist]]: Shotgun expert; getting more penetration and increased ammunition capacity. They also get increasingly more carrying capacity and un/welds doors faster.
** [[KillItWithFire 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.
** [[BoomHeadshot The Sharpshooter]]: Shoots Specimens in the head with pistols or semi-automatic rifles. It hurts them. A lot.
** [[StuffBlowingUp 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 [[GrenadeLauncher M79]].
** [[CombatMedic The Field Medic]]: The healer of the group; still more than capable to pile up bodies with their [[MoreDakka 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.
* CharlesAtlasSuperpower: One of the Support perk bonuses is increased carrying capacity. And even then, other perks can carry their fair share of weapons and ammo[[note]]in one particularly ironic example, players with the dosh to afford it can carry both an M79 and an M4 with M203 regardless of perk, even though in the real world the M203 was created specifically because the M79 was ''too heavy'' to carry alongside a rifle.[[/note]].
* ChristmasElves: The Clots became goblin-like grotesqueries of this trope for the Christmas events.
* CircusOfFear: The summer event's theme.
* CluckingFunny: Special Director Edmund Cook, aka the "Commando Chicken", a CloudCuckoolander movie cop who wore a giant chicken outfit for his office's party and then began killing Specimens while still wearing it. Then there's the [[Franchise/{{Terminator}} Chickenator]], a cyborg version of the same character.
* ColorCodedForYourConvenience: The Fleshpound has a bizarre glowing... thing on his chest that TurnsRed 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.
* CombatMedic:
** Even if you go Field Medic, you're going to spend a lot of time shooting at Zeds, unless things start to [[GoneHorriblyWrong 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, his weapons (at least the MP5 and MP7) 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 LightningBruiser, 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 [[RuleOfCool because why the hell not]]), but he only learns by being wounded himself and [[CombatSadomasochist has taken an unusual fascination in dishing out and receiving pain.]]
* CoolGuns: A large selection of such, ranging from the classic tommy gun to an overkill autoshotgun.
* CoolMask: A large number of the playable characters wear some kind of mask, mostly [[GasMaskMooks gas masks.]]
* CrazySurvivalist: 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.
* CreepyCircusMusic: The Summer Sideshow maps Abusement Park and Hellride feature variations of well-known melodies.
* CriticalExistenceFailure:
** 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 Christmas event, anyone who owns both ''Killing Floor'' and ''VideoGame/TeamFortress2'' 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 AlternateRealityGame surrounding the release of Portal 2 climaxed with the addition of KF-Aperture, a ''VideoGame/{{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.
---> [[foldercontrol]]

[[folder: "Well, it's been fun. Enjoy that thing you do. You know, dying." ]]

** To a lesser extent, [[LawyerFriendlyCameo there's one with]] RedOrchestra 2 in the form of [[WarReenactors 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 VideoGame/TeamFortress2. Similarly, the RedOrchestra spinoff, ''RisingStorm'', nets players a World War 2 GI and a Japanese grunt.
** The Twisted Christmas 2012 event adds a VideoGame/{{Dwarfs}} Axe to the game, which you can unlock by playing or buying that game.
* DamageDiscrimination: Players are FriendlyFireproof, 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.
* DangerouslyGenreSavvy: The Patriarch, after a patch, now reacts to multiple players trying to melee him to death to keep him from escaping. He will now flail about in a 360 attack that kills anyone caught in it in about two hits.
--> "So you're trying to do ''that'' again. Ehehehehaha!"
* DeadlyDoctor: Doctor Dave from the {{Steampunk}} DLC. He also has a NiceHat (top hat, of course).
* DeadlyLunge: 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.
* DeadWeight: The Bloat is grotesquely fat, but he's not really a zombie.
* DeadpanSnarker: 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 and teammates.: "You're pathetic! Like a bunch of bloody Millwall fans! "Who do you think you are, bleedin' ActionMan?"
* DefectorFromDecadence: The Lieutenant Masterson player-model is [[AllThereInTheManual apparently]] one of the last specimens created, who escaped and brought the army to take out Horzine. [[NiceJobBreakingItHero 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 Mad Scientists daughter 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 begun.
* DesperationAttack: A common tactic among doomed players is to throw all one's grenades at their feet when surrounded to [[TakingYouWithMe 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.
** Subverted with the Combat Medic, throwing your grenades at your feet when being swarmed will actually ''save you'' since it heals you and damages the Zeds over a short period of time. Firebugs can do much the same, as incendiary grenades + immunity to fire = easy escape.
* DevelopmentGag: Scattered around some of the maps are newspaper clippings that allow you to read the headlines. One such newspaper features the headline "SUSPECTED CULT" with an image of the Clot as it appeared in the original ''VideoGame/UnrealTournament2004'' mod.
** There's a poster on a lightpost in the Departed map with a picture of a cat saying: "Have you seen this cat? Because it's ''awesome''."
* DiegeticInterface: 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, [[AntiFrustrationFeatures when your magazine is about to run dry, both the gun's ammo counter and the reflex sight turn red]].
* DifficultySpike: Likely to compensate for fewer achievements than other holiday-themed events, most of the ones for the 2011 Halloween update specifically required players to play Bedlam (an extremely dark and cramped map) on Hard mode or above to unlock them.
** AntiFrustrationFeatures: In contrast, weapon-specific achievements for paid-for DLC weapons can be unlocked with either them or a non-paid-for counterpart.
** The Objective mode added with the 2013 Summer event expects you to fight off Fleshpounds starting from the ''second or third wave'' - which would be bad enough if you could handle them the normal way, but [[ViolationOfCommonSense now you have to stand in place while fighting them or ignore them while moving at a snail's pace]]. It's far from a majority by any metric, but there have been people asking Treyarch to remove level-completion achievements for Objective maps, simply because it's so much more difficult in a way people are having trouble adapting to.
* DingDongTheWitchIsDead: 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.
* DisasterDominoes: 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 [[StuffBlowingUp blow them up]].
* DiscOneNuke: 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 EverybodysDeadDave 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 OneManArmy moment.
* DoubleEntendre: Anything said by the Trader could - and is intended to be - taken as one.
** In the Abusement Park, there's machines hawking "Rainblow" condoms.
** Hook-handed Circus Clots will occasionally say "Just let me stick the tip in".
* DoubleUnlock: 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.
* DropDeadGorgeous: Okay, she's not ''dead'', per se, but the developers (or alternately, Kevin Clamely himself) are apparently [[{{Squick}} a bit too fond of the Stalker]]. Let's see: she's nearly naked, it's apparent her breasts use JigglePhysics when she dies in Zed Time[[note]]Though more realistic than usually seen in video games[[/note]], and the two events where they've reskinned the Zeds, she was a [[SexySantaDress Santa Babe]] (referred to as [[PunnyName Mrs. Claws]], naturally) and [[OfCorsetsSexy The Lovely Assistant]], respectively. And both reskins were [[BlondesAreEvil blonde]] and not horribly deformed. Usually.
* DummiedOut: The game has an incomplete-but-mostly-functional music player feature (likely left over from ''VideoGame/UnrealTournament2004''). Giving it a hotkey (such as by editing the user.ini in Killing Floor's System folder, finding the line F11= and changing it to F11=[=MusicMenu=]) can allow you to use it anywhere in the game by pressing the hotkey.
* DynamicDifficulty: 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, instead of spawning more often).
* EaglelandOsmosis: Inverted. Suburbia, the first official map confirmed to be outside of the UK (It's in an [[{{Eagleland}} 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.
* EmergencyWeapon: 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.
* EnemyChatter: Every enemy has a voice. [[TheUnintelligible Not always a clear one]], but every enemy says something.
* TheEngineer:
** The Support Specialist perk has elements of this, making you much more effective with the welding tool. Though you also get bonuses to [[ShotgunsAreJustBetter Shotgun use]].
** In the background, DLC character Aldridge worked on the assembly lines at Horzine. He was paid triple the normal wage for someone of his status and [[BystanderSyndrome didn't ask questions about the weird goings on]] - until a Specimen [[OhCrap broke open the door to his office.]] At that point, as it says in his bio, [[LetsGetDangerous "lunchtime was over."]]
* EvilLaugh: [[http://www.youtube.com/watch?v=ZXLuVIr0TWw#t=1m "Hahahaha, FEAR ME!"]]
* ExactlyWhatItSaysOnTheTin: Suicidal mode. See also HarderThanHard.
* ExcusePlot: So there's a [[MadScientist 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.
* ExpendableClone: 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 ''VideoGame/{{Blood}}'', with a dash of exploding on death a la ''VideoGame/Left4Dead'''s Boomer.
** Harold Lott is one to Harry Enfield's "Loadsamoney" sketch character.
** Harchier Spebbington is both this to IndianaJones and TheCameo from ''The Ball''.
* FanNickname: [=GLaDOSH=] for the [[VideoGame/{{Portal}} Trading Sphere]] that replaced the Trader during [=PotatoFoolsDay=].
* FlawedPrototype: All the specimens are failed attempts at creating {{supersoldier}}s.
* FootballHooligans: 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 [[LetsGetDangerous now he gets to use guns]].
* FourEyesZeroSoul: Dr. Kevin "The Patriarch" Clamely. It's more obvious on his loading screen artwork.
* FragileSpeedster: The Crawler and Stalker are both fairly fast, but both have almost no health.
** The Berserker perk has shades of this. Though he actually takes less damage than others, he also needs that to survive in melee combat. And he's faster than other perks.
* FreakOut: Mike Noble had one at a rave party after the specimens munched his girlfriend. He grabbed himself [[KatanasAreJustBetter a katana]] [[RoaringRampageOfRevenge and went to town.]]
* FreudianExcuse: 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".
* FriendlyFireproof:
** 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 VideoGame/TeamFortress2, 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.
* FullFrontalAssault: 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 [[{{Squick}} 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. Something involving ExecutiveMeddling forced them 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).
* GameMod:
** Started out as one to ''VideoGame/UnrealTournament2004''. Then the guys who did ''VideoGame/RedOrchestra'' (itself a GameMod 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 [[AscendedFanfic recognized mods]] - the first is stuff that is actually added to the game itself through patches, such as well-made maps. The second is the "whitelist", custom maps and mods that can be used without disabling Perk progression.
* GenreSavvy:
** Upon Crawlers appearing, characters will sometimes say "Oh great, creepy crawlies. I guess they hop, too."
** When the Sirens begin to appear, characters may say something to the effect of "Crap she's ugly. For god sakes, don't let her scream."
** The trader frequently advises players to get close to her next location near the end of the wave, which is a smart thing to do if you want enough time to consider what to buy. Or, in some cases, get any time to shop at all.
* GiveMeASword: Don't have the dosh for a [[MoreDakka 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). A higher-level Medic can pass off an [[DeathOfAThousandCuts MP7]], an [=MP5M=], or a Schniedzekk, all of which only weigh three blocks, to a Sharpshooter.
* GravityScrew: The Moonbase map, as would be expected. Sadly, third-party maps making use of similar low-gravity situations have yet to appear.
* GuideDangIt: 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.
* GunsAkimbo: 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.
* HandCannon: The [[ExactlyWhatItSaysOnTheTin Handcannon]].
* HalfHumanHybrid: 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 [[OnlyInItForTheMoney for the pay bonus.]] He seems to want to [[ImAHumanitarian take a bite out of]] [[TeethClenchedTeamwork Dr. Glover]].
* HalfTheManHeUsedToBe: The Hillbilly Crawler has nothing below the waist but its dangling spine.
* HairTriggerTemper: 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).
* HarderThanHard: In the first Christmas update, a difficulty above [[ExactlyWhatItSaysOnTheTin Suicidal]] was added; Hell on Earth.
* HealingShiv: The Field Medic's weapons are borderline examples. They are otherwise regular guns whose SecondaryFire mode launches a healing dart. Unlike the bullets, the darts are not HitScan and [[AwesomeButImpractical therefore it can be difficult to hit your teammates, especially when they're strafing and jumping around avoiding the Specimens.]] He also has gas grenades that hurt the Zeds but heal teammates.
* HitboxDissonance: The hitboxes for the first game's Zeds are simply [[http://img839.imageshack.us/img839/3448/cylinder.jpg enormous]].
* HoistByHisOwnPetard: 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.
* HoldTheLine: 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.
* HolidayMode: 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 MallSanta, the second seem to be clones of the real deal, and the later is a KillerRobot. All the above return for Twisted Christmas 2, which also features a new map, [[SlippySlideyIceWorld Ice Cave.]] And since Third time's a charm, the whole crew comes back for 2012... [[RecycledInSpace 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 [[VisualPun walking around Hell]]...
* HollywoodSilencer: 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=].
* HostileShowTakeover: GLaDOS got in contact with Horzine, it seems, providing some cloning vats for the Specimens. Then she decided to [[DevourTheDragon test]] them.
* HyperspaceArsenal: 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.
* IKnowMortalKombat: 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."
* ImplacableMan:
** 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.
* ImplausibleFencingPowers: At higher levels, the Berserker perk allows you to extend [=Zed-time=] through kills.
* IncrediblyLamePun: 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!''"
* InfernalRetaliation: Most of the stronger specimens have a lot more health than the Firebug's [[KillItWithFire 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 [[TurnsRed 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.
* InformedAbility: 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.
* InstantWinCondition: 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 [[RespawningEnemies infinitely spawning]] - you still have to clear out any of them that are already there.
* InterfaceScrew: 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.
* IntrepidMerchant: [=DLC=] character and ActionSurvivor 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 probably have been a good read.
* InvisibleWall: 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.
* JackOfAllStats: The Commando has elements of this. [[UnorthodoxReload He reloads any gun faster,]] [[StatOVision can see enemy health]] [[SpiderSense and cloaked stalkers,]] and can chain [[BulletTime Zed Time]] extensions. He uses the general-purpose [[MoreDakka assault rifles]] and tears though the swarming smaller Specimens. [[MasterOfNone He lacks heavy punch]] though, and is less effective than TheBerserker, [[StuffBlowingUp Demolitions]] or [[ShotgunsAreJustBetter 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 TheBerserker, a decent Sharpshooter can pick targets off better with fewer shots, and being able to see Specimens' health becomes a negligible ability when the Commando's best weapons merely chip away at their health.
** 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.
* KatanasAreJustBetter:
** Fast and lethal, though not quite having the bite of the [[ChainsawGood chainsaw]].
** Mike Noble has a preference for these, according to his bio.
* KillItWithFire: The Firebug perk's job.
** With the addition of the Flare Revolvers and the Trench Gun, everyone can get in on this now, 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.
* KnifeNut: The Berserker can chew apart early wave enemies with nothing but the weapon he spawned with, and get away with it.
* LeeroyJenkins:
** 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 [[MeaningfulName 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.
* LightningBruiser:
** There's the enraged Fleshpounds of course, and Scrakes with low health tend to charge the player at high speed and chainsaw them to bits.
** Then there's 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.'''
** To a lesser extent, 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.
* LostForever: The Potato achievements, and by extension its unlockable skin, although for the 2013 Halloween event they were brought back. Not strictly for the others, but to achieve them one must wait for the matching holiday to come around, which can feel like forever (doubly so for Halloween, since any given year has one of two mutually exclusive variations).
* LoveMakesYouEvil: The Patriarch views the specimens as his "children", and he gets ''[[PapaWolf 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-BigBad misappropriates military funding to clone his dead son.
* LuckBasedMission: 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. [[LevelGrinding A lot of them, actually]]. The amount of Stalkers spawned per game varies wildly. Even if a lot spawn, its almost certain another class [[FinaglesLaw 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 [[SpitefulAI 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 [[HoistByHisOwnPetard 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 [[LevelGrinding 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).
* MadDoctor: The Patriarch. [[AllThereInTheManual 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.
* MadeOfIron: 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 HardHead! Most specimens' heads will ''always'' [[BoomHeadshot 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).
* MadeOfExplodium: The Bloat usually explodes when killed. Many parallels are drawn to the [[VideoGame/Left4Dead Boomer]].
** Although he's more like the Spitter, using acid rather than an otherwise harmless liquid that attracts more enemies.
* MadeOfPlasticine:
** 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.
* MakeMeWannaShout: The Siren attacks via a horrid scream.
* MeatgrinderSurgery: Implied. [[AllThereInTheManual According to its bio]], the Scrake was designed as a medic. So why is it carrying a ''chainsaw''?
* TheMedic:
** The Field Medic perk makes you this, of course.
** Alfred Anderson is this in his bio, he was a paramedic at a London hospital.
* MightyGlacier: The Fleshpound is crazy strong and can take ''multiple'' rockets. He's also easy to run away from...[[BerserkButton until you piss him off]]. [[OhCrap And running away while still inside his field of view is one of the ways to piss him off]]. And once he gets pissed off he becomes [[LightningBruiser something else entirely]].
** Scrakes are a weaker version of the Fleshpound, but are far faster and still soak up rifle fire like no tomorrow.
** Both of these specimens can tank large amounts of explosives as well. Empty that six-shot revolver grenade launcher at a Fleshpound? If you're off-perk, you most likely just pissed him off.
* MonsterClown: What the Bloat and Fleshpound were reskinned as for the Summer Sideshow event.
* MoreDakka: 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.
* NailEm: The Hillbilly Horror Event added Vlad the Impaler (also known as the Vlad 9000), a magazine-fed nail [[ShotgunsAreJustBetter shotgun]] for the support specialist. The nails can ricochet and hit other specimens, which makes up for the [[ShortRangeShotgun terrible range]]. Halloween 2013 also added the [[NoAnimalsWereHarmed Seal Squeal Harpoon Gun]], which appears to be a large industrial rivet gun modified to fire explosive-rigged harpoons.
* NeverSplitTheParty: While not as bad as [[VideoGame/Left4Dead 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 death[[note]]Unless you're a high level Berserker or Sharpshooter- the former can fool the Fleshpound into following them around the map, gradually taking off health as they go, and can stun lock Scrakes by beating them over the head with the higher-end melee weapons. In the case of the Sharpshooter, 2-4 crossbow bolts through the head kills everything not a Patriarch, regardless of difficulty[[/note]]. 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.
* NightOfTheLivingMooks: The entire game, pretty much. Although they're [[OurZombiesAreDifferent not technically undead]].
* NoCelebritiesWereHarmed: Martel Halliday (the MissionControl 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 [[DeepSouth obvious accent]].
* NoFairCheating: Perks are disabled and unable to be leveled up if a game has any mutator that only spawns low-level {{mook}}s 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 [[HitAndRunTactics running around in circles shooting behind you]]!
* NoHeroDiscount: 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.
* NotUsingTheZWord: They're [[CallARabbitASmeerp "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 RecursiveAcronym.
** 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.
* OffscreenTeleportation: The spawn points of Specimens are basically wherever a player isn't looking. Even directly around the corner behind you.
** [[http://www.youtube.com/watch?v=_eHse8rnJR4 This]] poor guy had a Fleshpound spawn ''directly behind him''.
* OhCrap:
** 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!"
** Also "[[ExactlyWhatItSaysOnTheTin Oh crap]], run!"
** [[StuffBlowingUp "One in the pipe!"]]
** [[MoreDakka "Time for a more direct approach!"]]
* OneBulletClips: 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.
* OneSteveLimit: [[AvertedTrope Averted]], there are three Harolds: Harold Hunt, the SteamPunk support specalist, and the Harry Enfield CaptainErsatz. There's also two Daves, the SteamPunk medic and Dave "TheButcher" Roberts.
** Tripwire seems to have caught onto this, as Doctor Dave is now Doctor ''David''. Doesn't totally avert the trope, though.
* OurZombiesAreDifferent: Instead of the living dead, they're clones meant as military cannon fodder GoneHorriblyWrong.
* PoisonIsCorrosive: 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".
* PoliceBrutality: Constable Briar apparently has a history as a riot cop of "bludgeoning hippies" and "manhandling environmentalists." Such tendencies serve him well against the Specimens.
* PoweredArmor: Horzine Industries was apparently publicly developing a next-generation suit of combat armor simultaneously to the Specimens. Agent Wilkes, [=DLC=] character and British OvertOperative wears it, having secured it from their labs (though it offers no in-game benefit). According to his bio, Horzine "was great at multitasking." Security Officer Thorne also wears what looks to be the same armor minus the helmet and most of the arms.
* PowerLimiter: That...[[BuffySpeak 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.
* PowerupLetdown: The new Combat Shotgun, which costs 5 times as much as the regular Shotgun, shoots faster and has a pretty [[GunAccessories reflex sight]]. The tradeoff? Well... it reloads 35% SLOWER than the regular, holds 2 shells less, does the same damage per shell, has the same maximum amount of shells, and its ammo is also more expensive.
* PreMortemOneLiner:
** "One in the pipe!"
** "[[GatlingGood Wait right there]], [[MoreDakka 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!"
* PropRecycling: The tractor on KF-Farm is taken straight from RedOrchestra.
* RagtagBunchOfMisfits: 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.
* RareGuns: One of the assault rifles availables is a German [=MKb42=], the prototype of the [[http://en.wikipedia.org/wiki/Stg_44 StG-44]], the first assault rifle ever produced. It's a surprisingly good weapon (more powerful and precise than the [=AK47=] and the M4).
* RealIsBrown: There are shades of brown basically everywhere in a map. Some custom maps made official through patches are more colorful, though.
* RealityEnsues: All the specimens are recipients of an experimental process that enables them to [[ImplacableMan survive absurd/fatal levels of nervous damage]] and keep on trucking, in addition to other [[PsychoSerum unique]] [[HealingFactor survival]] [[InvisibilityCloak mechanisms]]. Where this trope kicks in is when it turns out that for all the genius engineering, [[RockBeatsLaser military hardware and bladed implements]] can still [[OffWithHisHead liberate them of their heads]], and while they don't die from that, they still bleed to death within a few seconds.
* RecoilBoost: 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.
* RecursiveAcronym: The Zed Eradication Device, also known as the Z.E.D.
* RecycledINSPACE: The 2012 Christmas event adds a map located on the moon, complete with low gravity.
* ReplacementGoldfish: Several million inhumanly tough deformed murderous goldfish.
* RevolversAreJustBetter: Twisted Christmas 2 brings a .44 Magnum revolver for the Sharpshooter. The Weapon Community Pack DLC adds the Flare Revolver for Firebugs. [[GunsAkimbo Like the other pistols, they can be dual-wielded.]]
** Said .44 Magnums are hilariously powerful, making them good sidearms for most players. The Sharpshooter gets [[UpToEleven a damage boost for them]].
* ReviveKillsZombie: The Combat Medic's grenades release healing gas that can also harm the specimens.
* RewardFromNowhere: 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.
* SexySantaDress: During the holiday events, the Stalker wears a very skimpy Santa Costume.
* SequelHook: The ''Transit'' - Objection 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.
* ShortRangeShotgun: Mostly averted - the hunting shotgun, in ''VideoGame/{{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 [[ShotgunsAreJustBetter shotgun]]. It has acceptable range and awkward spread, but the nails ricochet quite a bit. And it has a [[MundaneUtility 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 recieve heavy damage from the blast, while further/multiple targets are set on fire and take more damage trying to get closer.
* SmurfettePrinciple: While the Trader does play an important role in Killing Floor, Ash Harding, Mrs Foster, and Steampunk Mrs Foster 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 five 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.
* SnakeOilSalesman: The Mechanical Man (Summer Sideshow version of the Husk) is a robotic version of this trope. His product is fire.
* SniperPistol: 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, it's absolutely lethal. On lower difficulty levels, it's a perfectly usable weapon even late in the game, allowing skilled players to rack up headshot after headshot.
* SociopathicHero: 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.
* SoleSurvivor: Private Schnieder's squad was wiped out shortly after they were deployed. He had two options. [[DyingAlone Die alone]], or [[RoaringRampageOfRevenge 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.
* SoLongAndThanksForAllTheGear: 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.
* SoundtrackDissonance: The Christmas event map "Santa's Evil Lair" has you killing Zeds while the music from The Nutcracker plays in the background.
* {{Steampunk}}: The prize for unlocking 10/13 Summer achievements is a steampunk Mr. Foster skin.
** One of the prizes from the Steam Summer Sale (which can still be purchased otherwise) was the first Steampunk character pack, and as of Twisted Christmas 2 there is a second pack. Each of these new characters is identified by a particular class and even has the in-game class symbol on one arm.
** [[TheBerserker Reggie]]: [[BloodKnight A brutal]] [[PoliceBrutality ex-cop]] with a custom-made suit of scrap metal armor.
** [[FireBreathingWeapon Adam]]: The world's foremost PyroManiac[[PsychoForHire -for-hire,]] whose obsession saw him switch orphanages and later, prisons, alarmingly often.
** [[DeadlyDoctor Doctor Dave]]: A BackAlleyDoctor with a NiceHat.
** [[SniperRifle Peter]]: [[ProfessionalKiller A career assassin]], [[InTheBlood descended from a long line of such,]] and slightly concerned that the mutant masses may be too much for even him.
** [[StuffBlowingUp Quentin]]: [[MadBomber Lifelong demolitions expert,]] [[RetiredBadass former military man,]] [[NoodleIncident accidentally blew up a superior officer's dog.]] [[TheAtoner He thinks he can make up for that by cleansing England of the Specimens.]]
** [[ShotgunsAreJustBetter Harold]]: [[ThereAreNoTherapists Former relationship councilor.]] [[EverybodysDeadDave Now that all his customers are dead,]] [[BewareTheNiceOnes he's tapped into his dark side]] [[CrouchingMoronHiddenBadass in fighting the specimens,]] [[EvilMeScaresMe and he's kind of scared of it.]]
** [[CoolGuns Phil]]: [[TheEveryman Former supermarket shelf stocker,]] [[SmallNameBigEgo but he tells people he's]] [[RetiredBadass ex-special forces.]] But because of his excellent workout routine and the fact that [[IKnowMortalKombat he played a lot of]] [[FirstPersonShooter FPSs]] and read a lot of gun magazines, he's actually pretty good at killing Specimens.
** And special guest, SteamPunk DJ Scully! He's still pissed about the Specimens ruining his first big DJ gig.
* StuffBlowingUp: Leave this to the L.A.W. and the plentiful grenades, or the Demolitions Perk and its two dedicated [[GrenadeLauncher 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.
* SuicideAttack: 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.
* SurvivalHorror: 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.
* TakeThat: One of the TauntButton insults is "You're pathetic! Like a bunch of bloody [[http://en.wikipedia.org/wiki/Millwall_FC 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]] For those who don't, Wayne Rooney is player for Manchester United and has the reputation in the UK of being kind of an idiot.[[/note]]
* TakingYouWithMe: See DesperationAttack.
* TacticalRockPaperScissors: Because of resistances some Zeds have to certain weapons, it becomes really important in higher difficulties. Basically boils down to: explosives beat Fleshpound, [[ViolationOfCommonSense melee beats Scrake]], assault rifles beat Crawlers and Stalkers[[note]]in the sense that they are most efficient as they have large ammo counts, and those specimens come in large packs but are individually weak[[/note]], headshots beat Bloats, fire beats Scrakes, Gorefasts and Sirens[[note]]as they lose their special charge/screaming abilities when charred[[/note]].
* TauntButton: 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!")
* TitleDrop: Descriptions for community-made maps tend to shoehorn these in, regardless of whether the resulting phrase makes any sense [[MeaningfulName with context]] [[WordSaladTitle or not]].
* TookALevelInBadass: Pretty much par for the course for the survivors, especially for all the ActionSurvivor types.
* TurnsRed: The Flesh Pound literally turns red when he enters attack mode, and the Patriarch has a red shimmer when entering his invisible fleeing/attacking mode.
* UnstableEquilibrium: 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 [[FinaglesLaw no one else did already]]. Each shot should be carefully assesed, 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 [[AchillesHeel Achilles Heels]]: Scrakes, and [[HoistByHisOwnPetard his own explosives]].
* UpToEleven: The Fleshpound's aggression levels can apparently go this high, [[http://youtu.be/ZXLuVIr0TWw?t=1m11s according to it]].
* UnbreakableWeapons: Every Berserker weapon other than the Buzzsaw Bow has unlimited use, making them potentially very cost effective if you kill enough enemies with one.
* UnusableEnemyEquipment: Understandable, given that the few specimens who ''have'' weapons have them [[BladeBelowTheShoulder grafted on.]] [[AvertedTrope This did not stop]] [[KillItWithFire 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 grafted to its arm; the player version has a grip.
* ViolationOfCommonSense: 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''.
** [[http://www.youtube.com/watch?v=O_E1A_BpNKo Strapping several proximity bombs to your face]] is... [[SuicideAttack surprisingly effective]].
** Or to just back off and let a [[SingleStrokeBattle high-level]] [[FriendlySniper sharpshooter]] [[BoomHeadshot take care of it.]]
* VisibleInvisibility: 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.
* WakeUpCallBoss: Most new players underestimate the Fleshpound.
** Not to mention 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 [[GatlingGood Minigun]]-[[StuffBlowingUp Rocket launcher]] [[MoreDakka combi-weapon]] [[ArmCannon for a left arm]] that can turn invisible, run twice as fast as you, smash you across the room [[CombatTentacles in melee]], take multiple anti-armour rockets in the face [[MadeOfIron without dying]], summon more specimens and [[OhCrap heal himself]].
* WhiteGangBangers: Kevo the Chav, a slacker who spent most of his time drinking cheap lager and trying to work up the stones to shoplift. [[DoesNotKnowHisOwnStrength He was as surprised]] as anyone else when he found himself fighting a tide of angry mutants - [[ActionSurvivor 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.
* YouALLLookFamiliar: The specimens. HandWaved with cloning.
* YourHeadASplode: What happens if a Siren kills a player with her scream.
* ZombieApocalypse: More or less.
* ZombieGait: How Clots and Bloats move around. Gorefasts too, until they get close.
----
''"I'm cutting this one open, lads!"''
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