If you are reading this achievement, Gabe Newell has successfully launched Gnome Chompski into space.
Collect 100 gas cans in Scavenge.
Kill a pouncing Hunter with a shotgun.
Rescue three Survivors from a single rescue closet.
Instantly kill a Survivor as the Charger.
As the Spitter, spit on a Survivor who is pinned by a Hunter.
Earn a gold medal on any official survival map.
Earn a silver medal on any official survival map.
Earn a bronze medal on any official Survival map.
Revive an incapacitated teammate while a Tank is nearby.
Complete The Last Stand campaign in 13 minutes or less, without any Survivors dying.
Discover the hidden room in the Last Stand campaign
Survive The Last Stand campaign on any difficulty.
Plays games with free weekend players and helps them survive a campaign.
Play a Versus game on Dead Air from start to finish.
Collect three gifts dropped by Special Infected in Versus Mode.
Finish a campaign using only melee weapons.
Navigate the impound lot and reach the cemetery safe room without tripping any alarms.
Defend yourself at the crashed airliner without taking damage.
Navigate the sugar mill and reach the safe room without killing any Witches.
Revive 10 incapacitated Survivors while under the speed-boosting effects of adrenaline.
Survive the Cold Stream campaign on any difficulty.
Using the M60, kill 25 infected without letting go of the trigger.
Kill a Charger with a melee weapon while they are charging.
In a Survival round, get a medal only using melee weapons.
Have all 3 generators running at once in "The Sacrifice" finale.
As the Charger, bowl through the entire enemy team in a single charge.
As the Spitter, spit on a Survivor being choked by a Smoker.
Using a Molotov, burn a Clown leading at least 10 Common Infected.
Complete "The Sacrifice".
Have Bill sacrifice himself for the team.
Rescue Gnome Chompski from the Carnival.
Prove you are faster than Moustachio.
Prove you are stronger than Moustachio.
Kill 15 Infected with a single grenade launcher blast.
Collect 10 vials of Boomer vomit from infected CEDA agents you have killed.
Kill a Tank with melee weapons.
Play 6 Mutations.
Play the new Midnight Riders song on a jukebox.
As the Charger, grab a Survivor and carry them over 80 feet.
As the Charger, grab a Survivor and smash them into the ground for a solid 15 seconds.
As the Spitter, hit every Survivor with a single acid patch.
Collect 10 items dropped by a Fallen Survivor.
Open 5 foot lockers.
Cross the bridge finale in less than three minutes.
Win a game of Scavenge.
As the Jockey, ride the Survivors twice in a single life.
Honk the noses of 10 Clowns.
As the Jockey, ride a Survivor and steer them into a Spitter's acid patch.
Survive the Parish campaign.
Use every melee weapon to kill Common Infected.
Deploy an ammo upgrade and have your team use it.
Survive the Dark Carnival campaign.
Survive the Dead Center campaign.
Kill a Spitter before she is able to spit.
Use a bile bomb on a Tank.
Survive a campaign on Expert skill with Realism mode enabled.
As the Boomer, vomit on a Survivor without having direct line of sight with them.
Decapitate 200 Infected with a melee weapon.
With a sharp melee weapon, cut a Smoker's tongue before he ensnares you.
Kill a Jockey within 2 seconds of it jumping on a Survivor.
Destroy a Tank's rock in mid-air.
Kill the Witch bride with a single shotgun blast on expert difficulty.
As the Hunter, land a 25 damage pounce.
Kill 20 Jockeys with the shovel or pitchfork.
Survive for 10 minutes on any official map in Versus Survival.
Destroy 20 gascans as the Spitter.
Kill 53,599 infected. You made sure the dead won't rise anymore!
Escape Liberty Mall's Atrium before the first Tank appears
Kill one of each Uncommon Infected.
Earn a bronze medal on every official survival map
Earn a silver medal on every official survival map.
Earn a gold medal on every official survival map.
Survive for 30 minutes on any official survival map.
Kill a Witch using only a sharp melee weapon, without anyone getting incapacitated or killed.
On the concert finale, survive until the helicopter arrives without leaving the stage
Kill 10 swampy Mudmen while they are in the water.
As the Spitter, spit on a Survivor who is pinned by a Charger.
Knock off the heads of 18 infected with the golf club.
Survive The Passing Campaign.
Survive the Hard Rain campaign.
Stop the enemy team from collecting any gas cans during a Scavenge round.
In a Versus round, leave the saferoom to defibrillate a dead teammate.
Make a Survivor drop a gas can during overtime.
Cause 25 gas can drops as a Special Infected.
As the Charger, grab a Survivor and crash them through 8 chairs at the wedding.
Survive the Swamp Fever campaign.
Play 5 full games of Scavenge on The Port.
Kill a Special Infected with an exploding barrel.
As a Special Infected, incap someone who is trying to sacrifice themselves.
Survive all campaigns on Expert.
Form a team and beat an enemy team in 4v4 Versus or Scavenge.
Spread cheer by helping a free holiday player survive a campaign.
Kill 100 Common Infected with the chainsaw.
Revive 10 dead Survivors with the defibrillator.
Collect 15 gas cans in a single Scavenge round.
Ignite 50 Common Infected with incendiary ammo.
As the Jockey, ride a Survivor for more than 12 seconds.
Find the golden crowbars hidden in the Left 4 Dead 1 survival maps.
Kill a Tank only with damage from the original Survivors.
Survive The Last Stand campaign on Expert Realism.