Full list of all 65 Left 4 Dead achievements worth 1,500 gamerscore. It takes around 40-50 hours to unlock all of the achievements in the base game on Xbox 360.
The base game contains 50 achievements worth 1,000 Gamerscore, and there are 3 DLC packs containing 15 achievements worth 500 Gamerscore.
Kill 53,595 Infected.
Kill 1000 Infected with a mounted machine gun.
Single-handedly kill a Tank.
Save another Survivor from a Special Infected while on the ground.
As an Infected, incap a Survivor who has entered and left a safe room.
Kill a Witch with a single headshot.
Revive 50 incapacitated Survivors.
No Survivors take damage after contacting the rescue vehicle.
Survive all campaigns on Expert.
Play an entire campaign with no Survivors taking friendly fire damage.
Survive a campaign with no Survivors taking damage from Special Infected.
Survive any campaign on Expert.
All Survivors complete a campaign without being vomited on.
Finish a campaign without ever being healed.
Sneak past all Witches in a campaign without disturbing one.
Dole out 5000 total Survivor damage as a Special Infected.
Kill all four Survivors in one life while playing as a Tank.
Leave a safe room to save an incapped teammate and bring them back safely.
Rescue a Survivor trapped in a closet.
Heal 25 Survivors with a first aid kit.
Survive an entire campaign using only pistols.
Headshot a Hunter while he's leaping.
Drag a Survivor 100 feet with your tongue.
Pounce two different Survivors in one life as a Hunter.
Constrict two Survivors in one life as a Smoker.
Cover four Survivors with Boomer bile at once.
Survive the Blood Harvest campaign.
Heal a fellow Survivor when your own health is below 10.
Give pain pills to 10 Survivors.
Kill a Witch without any Survivor taking damage from her.
Kill an Infected with a single blow from behind.
Survive the Dead Air campaign.
Punch a Hunter as he is pouncing.
Set 101 Infected on fire.
Survive a campaign without being incapacitated.
Survive the Death Toll campaign.
Kill 10 Smokers as they are pulling helpless Survivors.
Rescue a Survivor from a Smoker's tongue before he takes damage.
Make 100 headshot kills.
Survive the No Mercy campaign.
Beat a campaign with all 4 Survivors.
Blow up 20 Infected in a single explosion.
Protect any Survivor from an attacking Infected 50 times.
Light a Tank with a Molotov.
Free yourself from a Smoker who has grabbed you with his tongue.
Shove a Boomer and then kill him without him splashing on anyone.
Light a Witch with a Molotov.
Shove a Hunter off of a pinned and helpless Survivor.
Kill a Tank without it dealing any damage to a Survivor.
You or another Survivor take no damage after being vomited on by a Boomer.
Kill 5,359 Infected in the Crash Course campaign.
Stun a Tank with an explosion in the Crash Course campaign.
Your team wipes all Survivors after the escape vehicle has opened in Crash Course.
Your team incapacitates three Survivors within five seconds in the Crash Course campaign.
Smoker pull a bile-covered Survivor until you hold him during Crash Course.
Win a Versus campaign of Crash Course.
Restart the generator within 30 seconds of it shutting off in the Crash Course campaign.
Pounce a Survivor for 25 points of damage in the Crash Course campaign.
Survive the Crash Course Campaign.
As a Tank hit 20 Survivors with a car in the Crash Course campaign.
Complete "The Sacrifice".
Kill a Special Infected with an exploding barrel.
Have Bill sacrifice himself for the team.
As a Special Infected, incap someone who is trying to sacrifice themselves.
Have all 3 generators running at once in "The Sacrifice" finale.