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