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