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