Full list of all 85 XCOM: Enemy Unknown achievements. It takes around 200 hours to unlock all of the achievements in the base game on Windows.
The base game contains 50 achievements, and there are 2 DLC packs containing 35 achievements.
Win the game from each of the 5 starting locations.
Beat the game in Ironman mode on Classic or Impossible Difficulty.
Beat the game on Impossible difficulty.
Have a soldier survive every mission in a full game.
Beat the game on any difficulty.
Beat the game on Classic difficulty.
Clear a UFO crash site with one soldier on Classic or Impossible difficulty.
Mind Control an Ethereal. Single player only.
In a single game, complete every Foundry project.
Shoot down 40 UFOs.
Play a multiplayer match against someone with this achievement.
Earn the "Excellent" rating in every performance category on a terror mission.
In a single game, complete every Research Project.
In a single game, shoot down one of each alien craft.
Make contact with the Ethereal hive mind.
Kill 500 aliens.
In a single game, complete every Autopsy.
Build the Gollop Chamber.
Find a soldier with the Gift.
Kill 50 aliens with explosive weapons.
Successfully assault an Overseer UFO.
Build the Hyperwave Relay.
Win a multiplayer match.
Acquire 1000 credits in one month.
Recover the Hyperwave Beacon.
Kill an alien while flying. Single player only.
Uncover the alien base's location.
Advance one of your soldiers to Colonel rank.
Complete a Very Hard abduction mission in five turns or less on Classic or Impossible difficulty.
Build a S.H.I.V.
Get satellite coverage over every country on one continent.
Build a Firestorm.
Build a suit of powered armor.
Win a mission with an all-female squad. Single player only.
Kill 150 aliens.
Stun an Outsider.
Build a Workshop.
Gain access to the lowest level in your base.
Staff the Research Labs with 80 scientists.
Staff the Engineering Department with 80 engineers.
Build a Laboratory.
Capture a live alien.
Launch a Satellite.
Build a base facility.
Complete the tutorial mission.
Fulfill a Council request.
Build an item.
Shoot down a UFO.
Complete a Research Project.
Complete a mission without losing a soldier.
Take your new ally into the final challenge.
Complete Gangplank.
Complete Confounding Light.
Complete Confounding Light with more than 3 turns left on the timer.
Complete Friends in Low Places.
Beat the game without buying a Squad Size upgrade (Classic+ difficulty)
Designate a highly decorated soldier as the Volunteer
Deal with the newest global threat
Complete Furies
Kill an unseen enemy detected by a specially modified soldier in single player
Field a squad consisting entirely of augmented soldiers and SHIVs (min. 4) and win the mission
Complete Deluge
Use Collateral Damage to blow up a car in single player
Kill a Muton Berserker in melee combat in single player
Kill an enemy as it is psionically attacking you in single player
Make certain of the new threat's location
Field a fully enhanced squad and win the mission
Have your special-duty soldier kill three enemies in the same mission
Field a squad with 4 augmented soldiers, each with a different base ability and win the mission
Jump two stories in one move in single player
Get a Soldier to have 5 modifications in single player
Cause an enemy to suicide
Field a squad where all members have at least two modifications (min. 4) and win the mission
Eliminate an enemy's shield and kill it on the same turn in single player
Kill an elite enemy Medic with explosive damage in single player
Kill an elite enemy Sniper with one of your own snipers in single player
Eliminate all alien waves
Get at least 4 kills with XCOM Base Security personnel
Proc Combat Rush on the entire squad (min. 4)
Beat a new special mission without losing any assets
Modify a soldier in single player
Deploy three tactical subsystems on a single soldier in single player
Augment a soldier in single player
Eradicate the infestation
Stop a squad member from suffocating in single player