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