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