Here is the full list of all 285 Killing Floor achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Kill 1 specimen ONLY while expending a full M4 Assault Rifle magazine
Kill 100 Sirens.
Kill a zed each with both the Bullpup and FN-Fal
Kill 5 Circus Crawlers with a Bullpup in one wave.
Kill a ZED with a direct (unexploded) shot from the Orca Bomb Propeller or the M-79/M32
Collect all 16 Z.E.D. Gun pieces
Kill 4 Stalkers in a game with the Vlad9000 Nailgun
In Co-op Mode, Use Syringe on Yourself 100 Times.
Kill a Scrake, a Fleshpound, and the Patriarch with the Claymore Sword within one map
Kill 5 Circus Bloats in one game.
Kill 1,000 Specimens.
Kill 1000 Hillbilly Zeds
Kill the Patriarch Before he has a Chance to Heal.
Kill 8 Specimens with One Grenade.
Aquire 5 Minutes of "Zed-Time".
[2010 Xmas] Kill 2 Christmas Gorefasts with a Melee weapon from behind in one wave.
Kill 3 Circus Clots in a wave with the Lever Action Rifle.
Survive 10 seconds after being screamed at by a Circus Siren on Hard or above.
[2010 Xmas] Get covered in Christmas Bloat Bile and live for 10 seconds on Hard, Suicidal, or Hell on Earth.
[2010 Xmas] Kill 20 Christmas Clots in one wave.
[2010 Xmas] Kill a Christmas Crawler with a Crossbow.
Give 1,000 Pounds to Teammates who have 50% of Your Cash or Less.
[2010 Xmas] Kill a Christmas Husk with any Pistol.
Kill 100 Specimens.
Cause a Specimen to Die by Luring them into Bloat Acid.
Kill the "Ring Leader" (Circus Patriarch)
[2010 Xmas] Kill the Christmas Patriarch.
Kill 4 Circus Zeds in 1 ZED time chain with a Melee weapon.
Finish off a Fleshpound using a Melee Attack.
Kill 15 XMas Clots, 5 xmas Stalkers, 5 XMas Crawlers, 1 XMas Siren and 1 XMas Bloat.
Kill 15 Specimens with a Fire Axe in a Single Wave.
[2010 Xmas] Kill 3 Christmas Zeds in 1 ZED time chain with a Melee weapon.
Kill 5 Hillbilly Zeds in 10 seconds with the Scythe or Axe
Kill a Circus Gorefast with a Melee weapon.
Kill 5 Halloween Specimens with any gun without reloading
Win a Long Game on West London on Normal Difficulty.
Win a Long Game on Manor on Normal Difficulty.
Win a Long Game on Biotics Lab on Normal Difficulty.
Win a Long Game on Farm on Normal Difficulty.
Win a Long Game on Offices on Normal Difficulty.
Complete a Long Game on all 5 Core Maps on Normal Difficulty.
Kill 200 Bloats.
Kill 20 Stalkers with Explosives.
Kill 2 Scrakes with a Chainsaw in a Single Wave.
Kill 25 Burning Specimens with a Crossbow.
Kill 10 Specimens Feeding on Dead Teammates Corpses.
Kill 4 Specimens with a Single Shot from a Hunting Shotgun.
As a Medic, Kill 8 Specimens using a Knife in a Single Wave.
Turn 500 Specimens into Giblets.
Turn 5 Fleshpounds into Giblets.
Complete 10 Waves when the Rest of your Team has Died.
Get All of your Perks up to Level 5.
Deliver the Killing Blow to the Patriarch with a L.A.W. Rocket.
Defeat the Patriarch on Suicidal.
Kill 10,000 Specimens.
Win a Long Game on West London on Hard Difficulty.
Win a Long Game on Manor on Hard Difficulty.
Win a Long Game on Farm on Hard Difficulty.
Win a Long Game on Offices on Hard Difficulty.
Win a Long Game on Biotics Lab on Hard Difficulty.
Complete a Long Game on all 5 Core Maps on Hard Difficulty.
Win a Long Game on West London on Suicidal Difficulty.
Win a Long Game on Manor on Suicidal Difficulty.
Win a Long Game on Farm on Suicidal Difficulty.
Win a Long Game on Offices on Suicidal Difficulty.
Win a Long Game on Biotics Lab on Suicidal Difficulty.
Complete a Long Game on all 5 Core Maps on Suicidal Difficulty.
Win a Long Game on Foundry, on Normal Difficulty.
Win a Long Game on Foundry, on Hard Difficulty.
Win a Long Game on Foundry, on Suicidal Difficulty.
Win a Long Game on Bedlam, on Normal Difficulty.
Win a Long Game on Bedlam, on Hard Difficulty.
Win a Long Game on Bedlam, on Suicidal Difficulty.
Win a Long Game on Wyre, on Normal Difficulty.
Win a Long Game on Wyre, on Hard Difficulty.
Win a Long Game on Wyre, on Suicidal Difficulty.
Complete a Long Game on all 3 Summer 2009 maps on Normal Difficulty.
Complete a Long Game on all 3 Summer 2009 maps on Hard Difficulty.
Complete a Long Game on all 3 Summer 2009 maps on Suicidal Difficulty.
As Demolitions, kill 1000 Specimens with the Pipebomb.
As Firebug, kill the Husk with the Flamethrower before he hurts anyone.
Kill the Patriarch when everyone is ONLY using Crossbows.
Turn 500 Zeds into Giblets using the M79.
Get 25 headshots in a row with the EBR while using the Laser Sight.
Kill 1000 Specimens with the SCAR.
Heal 200 teammates with the MP7's medication dart.
Kill 100 Fleshpounds with the AA12.
Kill 20 crawlers in mid-air with the M79.
Obliterate 10 Zeds at once with the Pipe Bomb.
Win a Long Game on West London on Hell on Earth Difficulty.
Win a Long Game on Manor on Hell on Earth Difficulty.
Win a Long Game on Farm on Hell on Earth Difficulty.
Win a Long Game on Offices on Hell on Earth Difficulty.
Win a Long Game on Biotics Lab on Hell on Earth Difficulty.
Win a Long Game on Foundry on Hell on Earth Difficulty.
Win a Long Game on Bedlam on Hell on Earth Difficulty.
Win a Long Game on Wyre on Hell on Earth Difficulty.
Win a Long Game on Biohazard on Normal Difficulty.
Win a Long Game on Biohazard on Hard Difficulty.
Win a Long Game on Biohazard on Suicidal Difficulty.
Win a Long Game on Biohazard on Hell on Earth Difficulty.
Win a Long Game on Crash on Normal Difficulty.
Win a Long Game on Crash on Hard Difficulty.
Win a Long Game on Crash on Suicidal Difficulty.
Win a Long Game on Crash on Hell on Earth Difficulty.
Win a Long Game on Departed on Normal Difficulty.
Win a Long Game on Departed on Hard Difficulty.
Win a Long Game on Departed on Suicidal Difficulty.
Win a Long Game on Departed on Hell on Earth Difficulty.
Win a Long Game on Filth's Cross on Normal Difficulty.
Win a Long Game on Filth's Cross on Hard Difficulty.
Win a Long Game on Filth's Cross on Suicidal Difficulty.
Win a Long Game on Filth's Cross on Hell on Earth Difficulty.
Win a Long Game on Hospital Horrors on Normal Difficulty.
Win a Long Game on Hospital Horrors on Hard Difficulty.
Win a Long Game on Hospital Horrors on Suicidal Difficulty.
Win a Long Game on Hospital Horrors on Hell on Earth Difficulty.
Win a Long Game on Icebreaker on Normal Difficulty.
Win a Long Game on Icebreaker on Hard Difficulty.
Win a Long Game on Icebreaker on Suicidal Difficulty.
Win a Long Game on Icebreaker on Hell on Earth Difficulty.
Win a Long Game on Mountain Pass on Normal Difficulty.
Win a Long Game on Mountain Pass on Hard Difficulty.
Win a Long Game on Mountain Pass on Suicidal Difficulty.
Win a Long Game on Mountain Pass on Hell on Earth Difficulty.
Win a Long Game on Suburbia on Normal Difficulty.
Win a Long Game on Suburbia on Hard Difficulty.
Win a Long Game on Suburbia on Suicidal Difficulty.
Win a Long Game on Suburbia on Hell on Earth Difficulty.
Win a Long Game on Waterworks on Normal Difficulty.
Win a Long Game on Waterworks on Hard Difficulty.
Win a Long Game on Waterworks on Suicidal Difficulty.
Win a Long Game on Waterworks on Hell on Earth Difficulty.
Complete all new map achievements on Normal Difficulty.
Complete all new map achievements on Hard Difficulty.
Complete all new map achievements on Suicidal Difficulty.
Complete all new map achievements on Hell On Earth Difficulty.
Get 1000 points of burn damage with the MAC-10.
Win a Long Game on Santa's Evil Lair on Normal Difficulty.
Win a Long Game on Santa's Evil Lair on Hard Difficulty.
Win a Long Game on Santa's Evil Lair on Suicidal Difficulty.
Win a Long Game on Santa's Evil Lair on Hell on Earth Difficulty.
[2010 Xmas] Land the killing blow on a Christmas Fleshpound with a Knife.
[2010 Xmas] Kill the Christmas Scrake with a Fire-based weapon.
[2010 Xmas] Kill 3 Christmas Bloats with the Bullpup in one wave.
[2010 Xmas] Kill a Christmas Siren with an undetonated LAW rocket.
[2010 Xmas] Kill 3 Christmas Stalkers with a Lever Action Rifle without reloading.
[2010 Xmas] Drop 3 Tier 3 weapons for others (with which they kill at least one Christmas Zed).
Unlock 10 of the 13 Christmas Achievements along with any Christmas Map achievement.
Expensive but delicious! Brought to you by Dr. Dougley and Lord Ned.
Win a Long Game on Aperture on Normal Difficulty.
Win a Long Game on Aperture on Hard Difficulty.
Win a Long Game on Aperture on Suicidal Difficulty.
Win a Long Game on Aperture on Hell on Earth Difficulty.
Get into GLaDOS' core on Aperture.
Win a Long Game on Abusement Park on Normal Difficulty.
Win a Long Game on Abusement Park on Hard Difficulty.
Win a Long Game on Abusement Park on Suicidal Difficulty.
Win a Long Game on Abusement Park on Hell on Earth Difficulty.
Kill 2 Circus Stalkers with a Melee weapon to the back in one wave.
Kill a Circus Scrake with a Crossbow.
Kill a Circus Husk with a LAW.
Land the killing blow on a Circus Fleshpound with a Pistol.
Drop 5 different Tier 2 weapons in one wave.
Kill 10 Circus Clots with a Fire-based weapon.
Unlock 10 of the 13 Circus Achievements along with any Abusement Park achievement.
Kill The Vampire Patriarch Ringmaster in Bedlam
Decapitate a burning Halloween specimen in Bedlam
Kill 250 Halloween Specimens in Bedlam
Win a Long Bedlam Match During the Halloween Event on Hard
Kill 25 Halloween Scrakes in Bedlam
Get all 6 achievements and unlock Commando Chicken
Kill 15 Husks with the Husk Cannon
Hit a Scrake with the M203 Rifle grenade to kill him
Heal others for 3000 points of health with the MP5 SMG
Kill 12 zeds with a full magazine from the Combat Shotgun
Kill a specimen with every shot from your Revolver for one magazine
Hold dual 9mm, dual hand cannons and Dual Revolvers
Beat Ice Cave on Normal Difficulty
Beat Ice Cave on Hard Difficulty
Beat Ice Cave on Suicidal Difficulty
Beat Ice Cave on Hell on Earth Difficulty
Kill 12 clots with one magazine without reloading (MK23)
Kill a zed that has injured a player (M7A3 rifle)
Kill one of each type of zed in one round (HSG Shotgun)
Kill 2 scrakes with one shot (M99)
Beat Hellride on Normal Difficulty
Beat Hellride on Hard Difficulty
Beat Hellride on Suicidal Difficulty
Beat Hellride on Hell on Earth Difficulty
Kill 6 Zeds with one magazine on an MKb42, without reloading
Heal yourself plus 5 other players with one grenade
Set a total of 200 Zeds on fire with the Trench Gun in Hillbilly Horror
Beat Hillbilly Horror on Normal Difficulty
Beat Hillbilly Horror on Hard Difficulty
Beat Hillbilly Horror on Suicidal Difficulty
Beat Hillbilly Horror on Hell on Earth Difficulty
Get the 6 Special Halloween Achievements plus 1 Hillbilly Horror Map Achievement to unlock the Grim Reaper
Free the souls of the 25 Gnomes hidden on Hillbilly Horror in 1 game
Kill 15 Hillbilly Crawlers in 1 game with the Tommy Gun or MKb42
Kill a Hillbilly Husk and another Hillbilly Zed in the same shot with the Buzzsaw Bow or M99
Set 3 Hillbilly Gorefasts on fire with the Flare Pistol or Trench Gun
Kill 30 Fleshpounds with the Dwarfs!? axe with back attacks
Kill 500 Zeds with the Schneidzekk Medic Gun while you are falling
Have 20 Zeds you slowed with the Z.E.D. gun killed
Beat Moonbase on Normal Difficulty
Beat Moonbase on Hard Difficulty
Beat Moonbase on Suicidal Difficulty
Beat Moonbase on Hell on Earth Difficulty
Get the Not-a-war-hammer Achievement in Dwarfs!?
Beat Steamland on Normal Difficulty
Beat Steamland on Hard Difficulty
Beat Steamland on Suicidal Difficulty
Beat Steamland on Hell on Earth Difficulty
Beat Steamland in Objective Mode on Normal Difficulty
Beat Steamland in Objective Mode on Hard Difficulty
Beat Steamland in Objective Mode on Suicidal Difficulty
Beat Steamland in Objective Mode on Hell on Earth Difficulty
[2013 Summer] Destroy all the Pukey the Clown dolls
[2013 Summer] Complete the Pop the Clot, the Strong Man and the Grenade Toss games
Have 5 Breaker Boxes 100% repaired at the same time
[2013 Summer] Protect the Ringmaster during the escort mission so that he does not get hit more than 15 times
Protect the ringmaster during the defense mission so that he does not get hit more than 15 times
Get all 3 gold bars without the carriers taking damage while they have them
Kill 4 different types of Zeds with headshots with 4 shots from the Long Musket or the M14 without reloading
Push a scrake back with the direct fire from a Hunting Shotgun or alt fire from the Multi-Chamber ZED Thrower
Kill 5 zeds in ZED time without reloading with Dr. T's LDS or Bullpup
Get 4 of 6 of the 2013 Summer Event in-game level Achievements, one Standard and one Objective Mode map completion Achievement, plus the Punk'd Achievement to unlock Steampunk Mrs. Foster
Beat Fright Yard on Normal Difficulty
Beat Fright Yard on Hard Difficulty
Beat Fright Yard on Suicidal Difficulty
Beat Fright Yard on Hell on Earth Difficulty
Beat Fright Yard in Objective Mode on Normal Difficulty
Beat Fright Yard in Objective Mode on Hard Difficulty
Beat Fright Yard in Objective Mode on Suicidal Difficulty
Beat Fright Yard in Objective Mode on Hell on Earth Difficulty
Attach the crane hook within 125 seconds
Collect all the bile without a contamination
Win Fuel on the first try
Destroy all 30 Cameras
Kill a Halloween Fleshpound and Scrake in the same explosion with the Seal Squeal Harpoon Bomber or the LAW
Use Bile or the Flamethrower to kill one of each Halloween Zed
Kill 10 Halloween zeds in explosions using the Seeker 6 or the M32 within 5 seconds
Beat Hell on Normal Difficulty
Beat Hell on Hard Difficulty
Beat Hell on Suicidal Difficulty
Beat Hell on Hell on Earth Difficulty
Beat Forgotten on Normal Difficulty
Beat Forgotten on Hard Difficulty
Beat Forgotten on Suicidal Difficulty
Beat Forgotten on Hell on Earth Difficulty
Win a short round on KF-Hell playing as or with Harchier Spebbington
Beat Siren's Belch on Normal Difficulty
Beat Siren's Belch on Hard Difficulty
Beat Siren's Belch on Suicidal Difficulty
Beat Siren's Belch on Hell on Earth Difficulty
Collect all the Beer Steins
Beat Stronghold on Normal Difficulty
Beat Stronghold on Hard Difficulty
Beat Stronghold on Suicidal Difficulty
Beat Stronghold on Hell on Earth Difficulty
Collect all the Treasure Bags
Beat Transit on Normal Difficulty
Beat Transit on Hard Difficulty
Beat Transit on Suicidal Difficulty
Beat Transit on Hell on Earth Difficulty
Beat Transit in Objective Mode on Normal Difficulty
Beat Transit in Objective Mode on Hard Difficulty
Beat Transit in Objective Mode on Suicidal Difficulty
Beat Transit in Objective Mode on Hell on Earth Difficulty
Transit - Get the Nitro to the Objective in 135 seconds or less
Transit - Kill 250 Zeds before completing the welding objective
Transit - Pick up the door key
Transit - Destroy all the DNA vials
Transit - Get all Objective achievements AND beat KFO Transit on Hard or above to unlock Dr Rachel Clamely.
Beat Clandestine on Normal Difficulty
Beat Clandestine on Hard Difficulty
Beat Clandestine on Suicidal Difficulty
Beat Clandestine on Hell Difficulty
Clandestine - Destroy 30 skulls
Beat ThrillsChills on Normal Difficulty
Beat ThrillsChills on Hard Difficulty
Beat ThrillsChills on Suicidal Difficulty
Beat ThrillsChills on Hell Difficulty
Destroy all (15) Snow Globes