Here is the full list of all 45 Aliens: Dark Descent achievements.
Keep all of your marines alive during a campaign.
Complete Mission 12.
Finish the game on Medium.
Complete Mission 11.
Complete Mission 10.
Kill every Queen during a campaign.
Complete Mission 09.
Complete Mission 07.
Complete Mission 08.
Advance a Sergeant to level 10.
During a campaign, advance each Marine Class to level 10.
Complete Mission 06.
Advance a Recon to level 10.
Advance a Gunner to level 10.
Unlock the APC.
Save a Marine from being incubated.
Advance a Tecker to level 10.
Complete Mission 04.
Complete Mission 05.
Complete Mission 03.
During a campaign, unlock every weapons.
Advance a Medic to level 10.
During a campaign, secure 5 survivors.
Make the ARC/APC run over an enemy.
Secure an unconscious marine.
Complete Mission 02.
Kill an enemy by using an explosive barrel.
Prevent a marine from being Abducted.
Have one Sentry kill at least 10 aliens.
Kill an enemy before they detect the squad.
Complete Mission 01.
During a campaign, kill 100 Xenomorphs.
Kill every Alien of a Massive Onslaught.
Finish the Prologue.
Finish the game on Hard.
Finish the game on Nightmare.
Finish the game on "No One Can Hear Them Scream" mode.
Lure a Queen into a Mine.
Gather all datapads.
Destroy 4 eggs with one grenade or an RPG shot.
Save a marine from dying of Bleeding.
In any mission, complete at least one objective with only one marine in the squad.
Remove a Trait from a marine.
During a campaign, unlock every Xeno Tech.
Have a marine with at least 2 Prostheses.