Full list of all 65 Left 4 Dead 2 achievements worth 1,500 gamerscore. It takes around 20-25 hours to unlock all of the achievements in the base game.
The base game contains 50 achievements worth 1,000 Gamerscore, and there are 2 DLC packs containing 15 achievements worth 500 Gamerscore.
Collect 15 gas cans in a single Scavenge round.
Kill a Charger with a melee weapon while they are charging.
In a Versus round, leave the saferoom to defibrillate a dead teammate.
Survive all campaigns on Expert.
Survive a campaign on Expert skill with Realism mode enabled.
Collect 100 gas cans in Scavenge.
As the Spitter, spit on a Survivor being choked by a Smoker.
Revive 10 incapacitated Survivors while under the speed-boosting effects of adrenaline.
As the Charger, bowl through the entire enemy team in a single charge.
As the Spitter, hit every Survivor with a single acid patch.
As the Jockey, ride a Survivor and steer them into a Spitter's acid patch.
In a Survival round, get a medal only using melee weapons.
Navigate the sugar mill and reach the safe room without killing any Witches.
Revive 10 dead Survivors with the defibrillator.
As the Charger, grab a Survivor and carry them over 80 feet.
Cause 25 gas can drops as a Special Infected.
Using a Molotov, burn a Clown leading at least 10 Common Infected.
Kill a Tank with melee weapons.
Cross the bridge finale in less than three minutes.
As the Jockey, ride the Survivors twice in a single life.
As the Charger, grab a Survivor and smash them into the ground for a solid 15 seconds.
As the Jockey, ride a Survivor for more than 12 seconds.
Kill 15 Infected with a single grenade launcher blast.
Make a Survivor drop a gas can during overtime.
Win a game of Scavenge.
Stop the enemy team from collecting any gas cans during a Scavenge round.
Navigate the impound lot and reach the cemetery safe room without tripping any alarms.
Collect 10 vials of Boomer vomit from infected CEDA agents you have killed.
Use every melee weapon to kill Common Infected.
Finish a campaign using only melee weapons.
Defend yourself at the crashed airliner without taking damage.
Kill 10 swampy Mudmen while they are in the water.
Rescue Gnome Chompski from the Carnival.
Prove you are stronger than Moustachio.
Prove you are faster than Moustachio.
Survive the Hard Rain campaign.
Survive the Swamp Fever campaign.
Kill a Jockey within 2 seconds of it jumping on a Survivor.
Ignite 50 Common Infected with incendiary ammo.
Kill one of each Uncommon Infected.
Survive the Dark Carnival campaign.
Honk the noses of 10 Clowns.
Kill 100 Common Infected with the chainsaw.
Survive the Dead Center campaign.
Decapitate 200 Infected with a melee weapon.
Survive the Parish campaign.
Deploy an ammo upgrade and have your team use it.
Use a bile bomb on a Tank.
Kill a Spitter before she is able to spit.
Form a team and beat an enemy team in 4v4 Versus or Scavenge.
As the Charger, grab a Survivor and crash them through 8 chairs at the wedding.
Play 6 Mutations.
Collect 10 items dropped by a Fallen Survivor.
Play 5 full games of Scavenge on The Port.
Using the M60, kill 25 infected without letting go of the trigger.
Knock off the heads of 18 infected with the golf club.
Play the new Midnight Riders song on a jukebox.
Open 5 foot lockers.
Survive The Passing Campaign.
Kill a Tank only with damage from the original Survivors.
Have all 3 generators running at once in "The Sacrifice" finale.
Kill a Special Infected with an exploding barrel.
Have Bill sacrifice himself for the team.
Complete "The Sacrifice".
As a Special Infected, incap someone who is trying to sacrifice themselves.