Killing Floor/YMMV

• Abridged Arena Array: Not as severe as it happens in other multiplayer games, but many games are played in WestLondon and Farm. Explanation: The easiest perk to level in the game is the Sharpshooter because headshots with the standard issue 9mm pistol count towards perk progress, which further gives damage bonuses to the pistol among other weapons. Both maps have plenty of open space for landing headshots before the zeds close in, and WestLondon is also among the brightest of the default maps. The most played custom maps, like ArcadeMall and MountainPass, are also wide open. Other maps that are played a lot are Wyre and BioticsLab. Tragically, other fine maps such as FilthsCross and IceBreaker are almost always ignored. And now that Mountain Pass is an official map, it's probably just as widely played as West London and Farm.
• Breather Level: The minute-long breaks between rounds. On the easiest difficulty, it's a minute and a half. However, if you are far away from the trader and low on ammo and/or armor, the break might be quite hectic in itself.
• Demonic Spiders:
  • Sirens. Their screams disarm explosives, cause exponential damage the closer you get, pierce armor, make your screen shake like crazy, and they have a good amount of health. Luckily they're fairly slow... but that doesn't matter when one comes up behind you and unleashes a bloodcurdling shriek right in your ear.
  • Bloats. They come with packs of weaker enemies and Interface Screw you, amplifying the damage you take and ensuring that you die horribly.
  • Scrakes and Fleshpounds. Both soak up enormous amounts of damage and are unstoppable once they begin charging towards the players. Because how zed health scales up with the amount of players, they are borderline unkillable without focus fire from the whole team.
• Game Breaker:
  • The Support Specialist class was this for a while, and it's still pretty bad. It gets all kinds of bonuses to shotguns, increased grenade capacity, increased grenade damage, increased weight capacity, increased welding speed... it's a Superpower Lottery of sorts.
    
    It's (long) since been nerfed by patches which greatly increased the threat posed by many specimens (namely Gorefasts, Scrakes and Flesh Pounds). Two new weapons were then added to put the other classes on even footing with the Support Specialist.
  • The Level Up content pack introduced the Demolitions class, whose easily spammable, rather cheap specimen-proximity-triggered pipebombs could be piled up and used to instantly kill the blissfully unaware Patriarch. Since nerfed, with smarter specimen/Patriarch pathfinding and a special "diminishing return" resistance for the 'Patty himself.
  • For the longest time, the Sharpshooter perk kept winding up with this status, as its higher tier weapons were, on headshot, usually extremely powerful to the point of flooring a six-player server Suicidal Difficulty Flesh Pound before he even got within 20 meters of getting a hit in edgewise and still have the firepower or attack speed to wipe out a good deal of the hordes of low priority targets, too. As of this writing, the lever-action rifle is the only weapon of the Sharpshooter perk's that hasn't been nerfed significantly yet.
    • Sharpshooters still have a bit of this status, because the crossbow doesn't change its price depending on level - high-leveled sharpshooters spawn with it, essentially getting their choice of either a weapon capable of killing nearly anything with one headshot, or an extra £600 towards anything else.
• Goddamned Bats:
  • Crawlers. GOOD GOD, Crawlers - especially if you're a Berserker. Their obnoxiously short hitboxes can completely ruin your momentum, practically guaranteeing you've got to fall back and switch to a different, less damaging but ranged weapon to dispatch them, leaving you wide open to all the other specimens. Appropriately, Crawlers are, in fact, human-spider hybrid hybrids.
  • Stalkers come in a distant second, since they're invisible until they start attacking or you're a Commando.
  • Clots can be annoying; five or six can swarm you, leaving you victim to Husks or Fleshpounds, or worse, the Patriach.
• Good Bad Bugs: Melee weapons have, since the game first came out, had a hidden "backstab" mechanic in the source code that was meant to cause double damage when attacking specimenss from behind. Problem was, this mechanic was bugged in such a way that it was always being applied. No one, save the developers, was aware of it for the most part until recently because they were very reluctant to fix it.
  
  The bug made the Berserker perk a lot more useful than it would be normally, but non-Berserker perks were also super-effective with melee weapons, which is what lead to the birth of the "Zerdic" or melee Medic. An upcoming balance patch intends to fix the bug, but also compensate for how much weaker melee weapons would become as a result.
• Memetic Mutation:
  • Everything the survivors say while handing out money.

"'Loads' a' money!"
"It's rainin' money!"
"Dosh! Grabbit while ye can, lads."
"Mawney mawney MAWNEY!"

• • Thanks to Garry's Mod videos, Briar and Masterson are this. They're Crazy Awesome and their power comes from DOSH.
• Most Annoying Sound:
  • Player characters say something nearly every time they reload, which happens quite often.
    • The support specialist spends most of the time he's not firing his shotgun in reloading his shotgun, guaranteeing a barrage of reloading warnings.
  • "They're all dead! It's tiiiiime to go shopping!"
  • BEEP! Some- BEEP! Some playe- BEEP! Someplayersfi-- BEEP!...Pipe bombs. BEEP!
  • The Siren scream, but that's a given.
  • Some players are not big fans of the default industrial metal game music which tends to get very repetitive very fast.
• Narm:
  • Scrake likes trousers.
  • This specimen video shows a case of this.
• So Bad It's Good:
  • The player characters' hammy voice acting would be weapons-grade Narm if it wasn't intentional (to say nothing of the Patriarch and, hoo boy, the trader's voice clips).

"Oi'm troyin' to 'eal you, not shag you!"
"You're all fur coat an' no knickers, bitches!"

"Look at you, running around like insects. I'll crush you like the pests you are!"

"Everything is so simple when you have a rocket launcher for an arm!"

"I like the big ones. Don't you?"

• • And then you get to the Patriarch...

"U KILLD MAH CHILL-DREN DUHRHUHUHUHU."
"YOU'RE RUINING EVERYTHING!"

• They Just Didn't Care: Some community-made maps were added into the game through updates. However, the fact that they're community-made is obvious due to spelling errors in map descriptions and logos or the HUD visible in menu screenshots. Past that, these maps also tend to play the Patriarch's theme, normally only played when fighting him, at any chance they get.