Here is the full list of all 66 Alien Swarm achievements.
Kill 100,000 Swarm.
Kill 250 Swarm with a Marksman Rifle.
Kill 250 Swarm with a Minigun.
Kill 100 Swarm with Laser Tripmines.
Kill 250 Swarm with a Tesla Cannon.
Awarded for finishing the Jacob campaign on Brutal difficulty.
Awarded for finishing the Jacob campaign on Insane difficulty.
Complete Sewer Junction within 1:30 on Normal difficulty or harder without any marines dying.
Complete 10 computer hacks without access being logged.
Kill 250 Swarm with a Grenade Launcher.
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.
Kill 250 Swarm with a Chainsaw.
Kill 100 Swarm with Hornet Barrages.
Kill 25,000 Swarm.
Complete Deima Surface Bridge within 2:30 on Normal difficulty or harder without any marines dying.
Kill 100 Swarm with Incendiary Mines.
Complete Cargo Elevator within 2:50 on Normal difficulty or harder without any marines dying.
Complete any mission on Brutal difficulty with Onslaught and Hardcore Friendly Fire enabled.
Complete Landing Bay within 1:25 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 mission on Normal difficulty or harder without receiving any damage.
Kill 15 Swarm with all four marines under the effects of a Damage Amp in a single mission.
Freeze 6 Swarm with a single Freeze Grenade.
Heal 300 points of damage in a single mission without dealing any non-melee damage to the Swarm.
Complete a campaign on Normal difficulty or harder without any marines dying.
Deploy 10 ammo stashes that are used by other marines.
Kill 6 Swarm with a single Grenade.
Stun 6 Swarm with a single Stun Grenade.
Kill 500 Swarm with deployable Sentry Guns.
Kill 5 Swarm with explosive barrels in a single mission.
Kill 250 Swarm with Twin Pistols.
Kill 5,000 Swarm.
Kill 250 Swarm with a Rail Rifle.
Kill 250 Swarm with a Shotgun.
Successfully perform 5 fast reloads in a row.
Kill 100 Swarm Grubs.
Kill 250 Swarm with a Vindicator.
Complete 10 wire hacks without access being logged.
Complete a mission with no friendly fire incidents. Four marines must be present in the mission.
Kill 250 Swarm with an Autogun.
Unlock all the available weapons.
Complete the Jacob's Rest campaign on Normal difficulty or harder.
Complete the Jacob's Rest campaign on Hard difficulty or harder.
Kill 250 Swarm with PDWs.
Kill 250 Swarm with a Flamethrower.
Kill 250 Swarm with a Prototype Rifle.
Destroy all Swarm Eggs in a mission without allowing any to hatch.
Kill 1,000 Swarm.
Complete a mission on Normal difficulty or harder without any marines dying.
Seal a door with the welder.
Guard the squad's tech so that he takes no damage during the hack.
Kill 25 drones without friendly fire. Four marines must be present in the mission.
Complete the Jacob's Rest campaign on Easy difficulty or harder.
Kill a Swarm Parasite with a melee attack.
Roll under a Swarm Ranger projectile.
Kill 250 Swarm with the Assault Rifle.
Cure an Infested marine.
Kill 20 Swarm with melee attacks in a single mission.
Heal all 4 marines with a single Heal Beacon.
Complete a mission with better than 90% accuracy.
Deliver the finishing blow to a Swarm Shieldbug.
Complete 2 co-op missions online. Earns a Team Fortress 2 parasite hat.
Finish a mission without the tech getting killed.
Kill a Swarm Boomer before it inflates.
Successfully perform a fast reload.