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