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