- Under The Weather
Use Bile or the Flamethrower to kill one of each Halloween Zed
- Ex-scientist
Collect all the bile without a contamination
- Most Bang for the Buck
Kill 10 Halloween zeds in explosions using the Seeker 6 or the M32 within 5 seconds
- Fire and Forget
Kill a Halloween Fleshpound and Scrake in the same explosion with the Seal Squeal Harpoon Bomber or the LAW
- Blinding Big Brother
Destroy all 30 Cameras
- Blooper Reel
Turn 500 Zeds into Giblets using the M79.
- Dot of Doom
Get 25 headshots in a row with the EBR while using the Laser Sight.
- Cracked the Nutcracker!
[2010 Xmas] Land the killing blow on a Christmas Fleshpound with a Knife.
- Golden Potato
Get into GLaDOS' core on Aperture.
- Can't Catch Me!
[2010 Xmas] Kill 2 Christmas Gorefasts with a Melee weapon from behind in one wave.
- Dignity for the Dead
Kill 10 Specimens Feeding on Dead Teammates Corpses.
- The Big One
Kill 2 scrakes with one shot (M99)
- We Have Ourselves a Cowboy
Hold dual 9mm, dual hand cannons and Dual Revolvers
- But It's All Red!
Collect all 16 Z.E.D. Gun pieces
- Eggnog Anyone?
[2010 Xmas] Get covered in Christmas Bloat Bile and live for 10 seconds on Hard, Suicidal, or Hell on Earth.
- Second Cousins
Beat Hillbilly Horror on Hard Difficulty
- Grim Reaper
Get the 6 Special Halloween Achievements plus 1 Hillbilly Horror Map Achievement to unlock the Grim Reaper
- Trench Warfare
Set a total of 200 Zeds on fire with the Trench Gun in Hillbilly Horror
- Meet Your Maker!
Kill 1000 Hillbilly Zeds
- Bloody Yanks
Kill 1 specimen ONLY while expending a full M4 Assault Rifle magazine
- British Superiority
Kill a zed each with both the Bullpup and FN-Fal
- Historical Remnants
Kill 6 Zeds with one magazine on an MKb42, without reloading
- Rippin' It Up
Kill a Hillbilly Husk and another Hillbilly Zed in the same shot with the Buzzsaw Bow or M99
- Creepy Crawlies
Kill 15 Hillbilly Crawlers in 1 game with the Tommy Gun or MKb42
- Nail'd!
Kill 4 Stalkers in a game with the Vlad9000 Nailgun
- Fiery Personality
Set 3 Hillbilly Gorefasts on fire with the Flare Pistol or Trench Gun
- I Am Become Death
Kill 5 Hillbilly Zeds in 10 seconds with the Scythe or Axe
- Soul Collector
Free the souls of the 25 Gnomes hidden on Hillbilly Horror in 1 game
- Flea Circus
Win a Long Game on Abusement Park on Normal Difficulty.
- Combat Medic
Kill a zed that has injured a player (M7A3 rifle)
- A Bloody Christmas Carol
Kill 15 XMas Clots, 5 xmas Stalkers, 5 XMas Crawlers, 1 XMas Siren and 1 XMas Bloat.
- Carving The Jack O' Lantern
Decapitate a burning Halloween specimen in Bedlam
- Zed October
Win a Long Bedlam Match During the Halloween Event on Hard
- Gone Mental
Win a Long Game on Bedlam, on Hard Difficulty.
- Sparkling in the Twilight
Kill The Vampire Patriarch Ringmaster in Bedlam
- The Scene is Zed
Kill 250 Halloween Specimens in Bedlam
- Trick, not Treat
Kill 5 Halloween Specimens with any gun without reloading
- A Bit Barmy
Win a Long Game on Bedlam, on Normal Difficulty.
- The Boss
Win a Long Game on Offices on Normal Difficulty.
- Still Alive
Win a Long Game on Aperture on Hard Difficulty.
- Punk'd
Unlock 10 of the 13 Circus Achievements along with any Abusement Park achievement.
- Windjammer Enthusiast
Survive 10 seconds after being screamed at by a Circus Siren on Hard or above.
- Juggling Act
Drop 5 different Tier 2 weapons in one wave.
- Taking Down the Big Top
Kill 4 Circus Zeds in 1 ZED time chain with a Melee weapon.
- Ringmaster
Kill the "Ring Leader" (Circus Patriarch)
- Lifting a Dumbell
Kill a Circus Husk with a LAW.
- The Big Hunt
Kill a Circus Scrake with a Crossbow.
- Elephant Gun
Land the killing blow on a Circus Fleshpound with a Pistol.
- Small Hands
Kill 3 Circus Clots in a wave with the Lever Action Rifle.
- Seeing Double
Kill 5 Circus Crawlers with a Bullpup in one wave.
- Clearing Clown Alley
Kill 5 Circus Bloats in one game.
- Assistant Homicide
Kill 2 Circus Stalkers with a Melee weapon to the back in one wave.
- Burning up the Midway
Kill 10 Circus Clots with a Fire-based weapon.
- Sparring with a Master
Kill a Circus Gorefast with a Melee weapon.
- Healing Touch
Heal 200 teammates with the MP7's medication dart.
- Let Them Burn
Get 1000 points of burn damage with the MAC-10.
- Master Surgeon
As a Medic, Kill 8 Specimens using a Knife in a Single Wave.
- Tin Man
Win a Long Game on Foundry, on Normal Difficulty.
- Lord of the Manor
Win a Long Game on Manor on Normal Difficulty.
- Thin-Ice Pirouette
Complete 10 Waves when the Rest of your Team has Died.
- The L.A.W. That Broke The Camel's Back
Deliver the Killing Blow to the Patriarch with a L.A.W. Rocket.
- It's What's Inside That Counts
Turn 500 Specimens into Giblets.
- Waste Disposal
Win a Long Game on Biohazard on Normal Difficulty.
- Warehouse Janitor
Win a Long Game on Crash on Normal Difficulty.
- Quarter Pounder With Ease
Turn 5 Fleshpounds into Giblets.
- Experimentilottacide
Kill 10,000 Specimens.
- Slight Drip
Win a Long Game on Waterworks on Normal Difficulty.
- Tis Better to Give than to Receive
[2010 Xmas] Drop 3 Tier 3 weapons for others (with which they kill at least one Christmas Zed).
- Fascist Dietitian
Kill 200 Bloats.
- Pub Crawl
Win a Long Game on West London on Normal Difficulty.
- Homer's Heroes
Kill 100 Sirens.
- Straight Rush
Kill the Patriarch Before he has a Chance to Heal.
- Careful Spender
Kill 4 Specimens with a Single Shot from a Hunting Shotgun.
- Lab Cleaner
Win a Long Game on Biotics Lab on Normal Difficulty.
- Keep Those Sneakers Off the Floor!
Kill 20 Stalkers with Explosives.
- Getting Chunky
Obliterate 10 Zeds at once with the Pipe Bomb.
- Deck the Halls with Buckets o' Blood
[2010 Xmas] Kill 3 Christmas Zeds in 1 ZED time chain with a Melee weapon.
- Rudolph, the Bloody Nosed Reindeer
[2010 Xmas] Kill a Christmas Crawler with a Crossbow.
- Self Medicator
In Co-op Mode, Use Syringe on Yourself 100 Times.
- Bitter Irony
Kill 2 Scrakes with a Chainsaw in a Single Wave.
- I Like To Watch
Aquire 5 Minutes of "Zed-Time".
- Too Close For Comfort
Finish off a Fleshpound using a Melee Attack.
- Who Brings a Gun to a Snow Ball Fight?
[2010 Xmas] Kill a Christmas Husk with any Pistol.
- Fending off Mrs. Claws
[2010 Xmas] Kill 3 Christmas Stalkers with a Lever Action Rifle without reloading.
- Back to Work
[2010 Xmas] Kill 20 Christmas Clots in one wave.
- Merry Friggin Christmas
[2010 Xmas] Kill the Christmas Patriarch.
- Social Outburst
Kill 8 Specimens with One Grenade.
- Toasted Jack Frost
[2010 Xmas] Kill the Christmas Scrake with a Fire-based weapon.
- Philanthropist
Give 1,000 Pounds to Teammates who have 50% of Your Cash or Less.
- Experimentimillicide
Kill 1,000 Specimens.
- Random Axe of Kindness
Kill 15 Specimens with a Fire Axe in a Single Wave.
- Flaming Hell, That was Close
As Firebug, kill the Husk with the Flamethrower before he hurts anyone.
- It's Not Easy Being Greasy
Cause a Specimen to Die by Luring them into Bloat Acid.
- Experimenticenticide
Kill 100 Specimens.
- Mr. Perky
Get All of your Perks up to Level 5.
- Complete Barking
Win a Long Game on Bedlam, on Suicidal Difficulty.
- Squirrel King of the Dark Forest
Win a Long Game on Wyre, on Normal Difficulty.
- Raccoon King of the Dark Forest
Win a Long Game on Wyre, on Hard Difficulty.
- Bear King of the Dark Forest
Win a Long Game on Wyre, on Suicidal Difficulty.
- Long, Hot Summer
Complete a Long Game on all 3 Summer 2009 maps on Normal Difficulty.
- Summer of 2009
Complete a Long Game on all 3 Summer 2009 maps on Hard Difficulty.
- And Back to School
Complete a Long Game on all 3 Summer 2009 maps on Suicidal Difficulty.
- Pound This
Kill 100 Fleshpounds with the AA12.
- Demonic King of the Manor
Win a Long Game on Manor on Hell on Earth Difficulty.
- Demon Farmer
Win a Long Game on Farm on Hell on Earth Difficulty.
- Boss from Hell
Win a Long Game on Offices on Hell on Earth Difficulty.
- Scientist from Hell
Win a Long Game on Biotics Lab on Hell on Earth Difficulty.
- Diablo Steel Man
Win a Long Game on Foundry on Hell on Earth Difficulty.
- Commit-ed for life
Win a Long Game on Bedlam on Hell on Earth Difficulty.
- Wolf King of the Dark Forest
Win a Long Game on Wyre on Hell on Earth Difficulty.
- Waste of Space
Win a Long Game on Biohazard on Suicidal Difficulty.
- Wasted
Win a Long Game on Biohazard on Hell on Earth Difficulty.
- Warehouse Forklift Operator
Win a Long Game on Crash on Hard Difficulty.
- Warehouse Foreman
Win a Long Game on Crash on Suicidal Difficulty.
- Warehouse Manager
Win a Long Game on Crash on Hell on Earth Difficulty.
- Departure Lounge
Win a Long Game on Departed on Hard Difficulty.
- Dear Departed
Win a Long Game on Departed on Hell on Earth Difficulty.
- Missed Connection
Win a Long Game on Filth's Cross on Hard Difficulty.
- Train Wreck
Win a Long Game on Filth's Cross on Suicidal Difficulty.
- Gimme a Plaster!
Win a Long Game on Hospital Horrors on Normal Difficulty.
- I'm Dying Here!
Win a Long Game on Hospital Horrors on Suicidal Difficulty.
- Not Dead Yet!
Win a Long Game on Hospital Horrors on Hell on Earth Difficulty.
- Ice Cube
Win a Long Game on Icebreaker on Normal Difficulty.
- Iceberg
Win a Long Game on Icebreaker on Suicidal Difficulty.
- Comet
Win a Long Game on Icebreaker on Hell on Earth Difficulty.
- Daytrip
Win a Long Game on Mountain Pass on Normal Difficulty.
- Gone Camping
Win a Long Game on Mountain Pass on Hard Difficulty.
- Mountaineer
Win a Long Game on Mountain Pass on Suicidal Difficulty.
- Park Ranger
Win a Long Game on Mountain Pass on Hell on Earth Difficulty.
- Neighborhood Watch
Win a Long Game on Suburbia on Normal Difficulty.
- Private Security
Win a Long Game on Suburbia on Hard Difficulty.
- Vigilante
Win a Long Game on Suburbia on Suicidal Difficulty.
- SWAT
Win a Long Game on Suburbia on Hell on Earth Difficulty.
- Burst Pipe
Win a Long Game on Waterworks on Hard Difficulty.
- Pressure Failure
Win a Long Game on Waterworks on Suicidal Difficulty.
- Floodgate to Hell
Win a Long Game on Waterworks on Hell on Earth Difficulty.
- Piece of Cake
Complete all new map achievements on Normal Difficulty.
- Pound Cake
Complete all new map achievements on Hard Difficulty.
- Fruit Cake
Complete all new map achievements on Suicidal Difficulty.
- Devil Cake
Complete all new map achievements on Hell On Earth Difficulty.
- Walking in A Winter Horror Land
Win a Long Game on Santa's Evil Lair on Normal Difficulty.
- Silent Night, Evil Night
Win a Long Game on Santa's Evil Lair on Hard Difficulty.
- I'm Dreaming of a Red Christmas
Win a Long Game on Santa's Evil Lair on Suicidal Difficulty.
- Grandma got Eaten by a Reindeer
Win a Long Game on Santa's Evil Lair on Hell on Earth Difficulty.
- That's not Santa!
[2010 Xmas] Kill 3 Christmas Bloats with the Bullpup in one wave.
- Not So Silent Night
[2010 Xmas] Kill a Christmas Siren with an undetonated LAW rocket.
- Uber Tuber
Expensive but delicious! Brought to you by Dr. Dougley and Lord Ned.
- Science Got Done
Win a Long Game on Aperture on Normal Difficulty.
- I'm Making a Note Here, Huge Success
Win a Long Game on Aperture on Hell on Earth Difficulty.
- Dog and Pony Show
Win a Long Game on Abusement Park on Hard Difficulty.
- 3 Ring Circus
Win a Long Game on Abusement Park on Suicidal Difficulty.
- On Top of the Big Top
Win a Long Game on Abusement Park on Hell on Earth Difficulty.
- Burning Irony
Kill 15 Husks with the Husk Cannon
- Finish Him
Hit a Scrake with the M203 Rifle grenade to kill him
- I love ze Healing not ze Hurting
Heal others for 3000 points of health with the MP5 SMG
- Italian Meat Pasta
Kill 12 zeds with a full magazine from the Combat Shotgun
- Feeling Lucky?
Kill a specimen with every shot from your Revolver for one magazine
- Stay Frosty
Beat Ice Cave on Hard Difficulty
- On the Rocks
Beat Ice Cave on Suicidal Difficulty
- Spec Ops
Kill 12 clots with one magazine without reloading (MK23)
- Fugly
Kill one of each type of zed in one round (HSG Shotgun)
- Stuck in Limbo
Beat Hellride on Hard Difficulty
- Demonic Road
Beat Hellride on Suicidal Difficulty
- Explosion of Love
Heal yourself plus 5 other players with one grenade
- Have my axe
Kill 30 Fleshpounds with the Dwarfs!? axe with back attacks
- One Small Step for Man
Kill 500 Zeds with the Schneidzekk Medic Gun while you are falling
- Game Over, Man!
Have 20 Zeds you slowed with the Z.E.D. gun killed
- Gimli That Axe!
Get the Not-a-war-hammer Achievement in Dwarfs!?
- Modified Psychoacceleration Achiever
Beat Steamland on Hard Difficulty
- Advanced Omega Wave Resonance Explorer
Beat Steamland on Hell on Earth Difficulty
- Simplified Force Adhesion Afficianado
Beat Steamland in Objective Mode on Normal Difficulty
- Oscillating Hydrogen Transition Achiever
Beat Steamland in Objective Mode on Hard Difficulty
- Alpha Wave Osteooxidation Activator
Beat Steamland in Objective Mode on Suicidal Difficulty
- Tachyon Cytoneutralization Explorer
Beat Steamland in Objective Mode on Hell on Earth Difficulty
- Hide and go Puke
[2013 Summer] Destroy all the Pukey the Clown dolls
- Arcade Gamer
[2013 Summer] Complete the Pop the Clot, the Strong Man and the Grenade Toss games
- Full Charge
Have 5 Breaker Boxes 100% repaired at the same time
- Extended Motion Protector
[2013 Summer] Protect the Ringmaster during the escort mission so that he does not get hit more than 15 times
- Guardian Assault Protector
Protect the ringmaster during the defense mission so that he does not get hit more than 15 times
- Golden 3 Crown Note
Get all 3 gold bars without the carriers taking damage while they have them
- Turbo Executioner
Kill 5 zeds in ZED time without reloading with Dr. T's LDS or Bullpup
- Mrs. Punkd
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
- Gang Crew
Beat Fright Yard on Hard Difficulty
- Stevedore
Beat Fright Yard on Suicidal Difficulty
- Fork Lift Operator
Beat Fright Yard in Objective Mode on Normal Difficulty
- Crane Operator
Beat Fright Yard in Objective Mode on Suicidal Difficulty
- Shipping Magnate
Beat Fright Yard in Objective Mode on Hell on Earth Difficulty
- King Minos
Beat Hell on Hard Difficulty
- Cerberus
Beat Hell on Suicidal Difficulty
- Amnesia
Beat Forgotten on Suicidal Difficulty
- Dementia
Beat Forgotten on Hell on Earth Difficulty
- Master Brewer
Beat Siren's Belch on Suicidal Difficulty
- Peasant
Beat Stronghold on Normal Difficulty
- Prince
Beat Stronghold on Suicidal Difficulty
- King
Beat Stronghold on Hell on Earth Difficulty
- Business Class
Beat Transit on Suicidal Difficulty
- Long weekend
Beat Transit in Objective Mode on Hard Difficulty
- Serious vacation
Beat Transit in Objective Mode on Suicidal Difficulty
- Moved to Paris!
Beat Transit in Objective Mode on Hell on Earth Difficulty
- Doctor WHO??
Transit - Get all Objective achievements AND beat KFO Transit on Hard or above to unlock Dr Rachel Clamely.
- Burned out
Beat Clandestine on Suicidal Difficulty
- Hangover from Hell
Beat Clandestine on Hell Difficulty
- Hollow of Horror
Beat ThrillsChills on Hell Difficulty