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