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