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