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