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