Here is the full list of all 66 Alien Swarm achievements.
Kill 100,000 Swarm.
Heal 300 points of damage in a single mission without dealing any non-melee damage to the Swarm.
Complete 10 computer hacks without access being logged.
Complete Timor Station within 4:25 on Normal difficulty or harder without any marines dying.
Complete SynTek Residential within 2:30 on Normal difficulty or harder without any marines dying.
Complete Rydberg Reactor within 3:10 on Normal difficulty or harder without any marines dying.
Complete Deima Surface Bridge within 2:30 on Normal difficulty or harder without any marines dying.
Complete Landing Bay within 1:25 on Normal difficulty or harder without any marines dying.
Kill 100 Swarm Grubs.
Kill a Swarm Parasite with a melee attack.
Cure an Infested marine.
Awarded for finishing the Jacob campaign on Brutal difficulty.
Kill 250 Swarm with a Tesla Cannon.
Complete Sewer Junction within 1:30 on Normal difficulty or harder without any marines dying.
Complete any mission on Brutal difficulty with Onslaught and Hardcore Friendly Fire enabled.
Complete 10 wire hacks without access being logged.
Complete a campaign on Normal difficulty or harder without any marines dying.
Kill 25,000 Swarm.
Complete Cargo Elevator within 2:50 on Normal difficulty or harder without any marines dying.
Deploy 10 ammo stashes that are used by other marines.
Kill 15 Swarm with all four marines under the effects of a Damage Amp in a single mission.
Guard the squad's tech so that he takes no damage during the hack.
Heal all 4 marines with a single Heal Beacon.
Complete a mission with better than 90% accuracy.
Complete the Jacob's Rest campaign on Normal difficulty or harder.
Complete the Jacob's Rest campaign on Hard difficulty or harder.
Awarded for finishing the Jacob campaign on Insane difficulty.
Complete the Jacob's Rest campaign on Easy difficulty or harder.
Destroy all Swarm Eggs in a mission without allowing any to hatch.
Unlock all the available weapons.
Kill a Swarm Boomer before it inflates.
Deliver the finishing blow to a Swarm Shieldbug.
Roll under a Swarm Ranger projectile.
Kill 100 Swarm with Incendiary Mines.
Kill 250 Swarm with a Prototype Rifle.
Stun 6 Swarm with a single Stun Grenade.
Kill 100 Swarm with Laser Tripmines.
Freeze 6 Swarm with a single Freeze Grenade.
Kill 250 Swarm with a Vindicator.
Kill 5 Swarm with explosive barrels in a single mission.
Kill 5,000 Swarm.
Kill 100 Swarm with Hornet Barrages.
Kill 250 Swarm with a Grenade Launcher.
Kill 250 Swarm with a Marksman Rifle.
Kill 250 Swarm with a Chainsaw.
Kill 250 Swarm with a Flamethrower.
Kill 250 Swarm with a Rail Rifle.
Kill 250 Swarm with PDWs.
Kill 250 Swarm with an Autogun.
Kill 250 Swarm with a Shotgun.
Kill 500 Swarm with deployable Sentry Guns.
Kill 1,000 Swarm.
Kill 250 Swarm with a Minigun.
Kill 250 Swarm with Twin Pistols.
Kill 250 Swarm with the Assault Rifle.
Successfully perform 5 fast reloads in a row.
Kill 20 Swarm with melee attacks in a single mission.
Kill 6 Swarm with a single Grenade.
Complete a mission with no friendly fire incidents. Four marines must be present in the mission.
Complete 2 co-op missions online. Earns a Team Fortress 2 parasite hat.
Kill 25 drones without friendly fire. Four marines must be present in the mission.
Successfully perform a fast reload.
Complete a mission on Normal difficulty or harder without receiving any damage.
Finish a mission without the tech getting killed.
Complete a mission on Normal difficulty or harder without any marines dying.
Seal a door with the welder.