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