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