Here is the full list of all 66 Alien Swarm achievements.
Kill 100,000 Swarm.
Kill 100 Swarm Grubs.
Complete 10 computer hacks without access being logged.
Kill 25,000 Swarm.
Kill a Swarm Parasite with a melee attack.
Complete 10 wire hacks without access being logged.
Complete any mission on Brutal difficulty with Onslaught and Hardcore Friendly Fire enabled.
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.
Complete a campaign on Normal difficulty or harder without any marines dying.
Stun 6 Swarm with a single Stun Grenade.
Kill 250 Swarm with a Vindicator.
Kill 100 Swarm with Incendiary Mines.
Kill 100 Swarm with Laser Tripmines.
Kill 250 Swarm with a Prototype Rifle.
Complete a mission on Normal difficulty or harder without receiving any damage.
Kill 500 Swarm with deployable Sentry Guns.
Kill 250 Swarm with a Minigun.
Kill 250 Swarm with a Chainsaw.
Kill 250 Swarm with a Shotgun.
Kill 250 Swarm with PDWs.
Kill 250 Swarm with Twin Pistols.
Kill 250 Swarm with a Rail Rifle.
Kill 250 Swarm with a Grenade Launcher.
Kill 250 Swarm with a Tesla Cannon.
Kill 5,000 Swarm.
Kill 100 Swarm with Hornet Barrages.
Kill 250 Swarm with a Marksman Rifle.
Cure an Infested marine.
Heal 300 points of damage in a single mission without dealing any non-melee damage to the Swarm.
Kill 20 Swarm with melee attacks in a single mission.
Awarded for finishing the Jacob campaign on Brutal difficulty.
Awarded for finishing the Jacob campaign on Insane difficulty.
Complete Deima Surface Bridge within 2:30 on Normal difficulty or harder without any marines dying.
Kill 6 Swarm with a single Grenade.
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 25 drones without friendly fire. Four marines must be present in the mission.
Successfully perform 5 fast reloads in a row.
Complete Timor Station within 4:25 on Normal difficulty or harder without any marines dying.
Complete the Jacob's Rest campaign on Hard difficulty or harder.
Unlock all the available weapons.
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.
Destroy all Swarm Eggs in a mission without allowing any to hatch.
Complete Rydberg Reactor within 3:10 on Normal difficulty or harder without any marines dying.
Complete a mission on Normal difficulty or harder without any marines dying.
Complete a mission with no friendly fire incidents. Four marines must be present in the mission.
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 Flamethrower.
Kill 1,000 Swarm.
Kill 5 Swarm with explosive barrels in a single mission.
Freeze 6 Swarm with a single Freeze Grenade.
Kill 250 Swarm with an Autogun.
Kill 250 Swarm with the Assault Rifle.
Roll under a Swarm Ranger projectile.
Deploy 10 ammo stashes that are used by other marines.
Kill a Swarm Boomer before it inflates.
Deliver the finishing blow to a Swarm Shieldbug.
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.
Complete a mission with better than 90% accuracy.
Finish a mission without the tech getting killed.
Successfully perform a fast reload.
Seal a door with the welder.