Full list of all 85 XCOM: Enemy Unknown achievements. It takes around 80-100 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.
Achievements they've won
Achievements they've not won
Complete a Very Hard abduction mission in five turns or less on Classic or Impossible difficulty.
Clear a UFO crash site with one soldier on Classic or Impossible difficulty.
Beat the game in Ironman mode on Classic or Impossible Difficulty.
Win the game from each of the 5 starting locations.
Beat the game on Classic difficulty.
Beat the game on Impossible difficulty.
Play a multiplayer match against someone with this achievement.
Win a multiplayer match.
Have a soldier survive every mission in a full game.
Shoot down 40 UFOs.
In a single game, complete every Research Project.
Beat the game on any difficulty.
Make contact with the Ethereal hive mind.
Mind Control an Ethereal. Single player only.
In a single game, shoot down one of each alien craft.
Kill 50 aliens with explosive weapons.
In a single game, complete every Foundry project.
Find a soldier with the Gift.
Build a S.H.I.V.
Kill an alien while flying. Single player only.
Win a mission with an all-female squad. Single player only.
Staff the Research Labs with 80 scientists.
Staff the Engineering Department with 80 engineers.
Build the Gollop Chamber.
In a single game, complete every Autopsy.
Successfully assault an Overseer UFO.
Build the Hyperwave Relay.
Acquire 1000 credits in one month.
Get satellite coverage over every country on one continent.
Kill 500 aliens.
Recover the Hyperwave Beacon.
Gain access to the lowest level in your base.
Build a suit of powered armor.
Build a Firestorm.
Advance one of your soldiers to Colonel rank.
Uncover the alien base's location.
Earn the "Excellent" rating in every performance category on a terror mission.
Stun an Outsider.
Kill 150 aliens.
Build a Laboratory.
Build a Workshop.
Capture a live alien.
Fulfill a Council request.
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.
Complete Friends in Low Places.
Complete Confounding Light.
Take your new ally into the final challenge.
Complete Confounding Light with more than 3 turns left on the timer.
Beat the game without buying a Squad Size upgrade (Classic+ difficulty)
Designate a highly decorated soldier as the Volunteer
Kill an unseen enemy detected by a specially modified soldier in single player
Proc Combat Rush on the entire squad (min. 4)
Deploy three tactical subsystems on a single soldier in single player
Field a squad consisting entirely of augmented soldiers and SHIVs (min. 4) and win the mission
Field a squad with 4 augmented soldiers, each with a different base ability and win the mission
Deal with the newest global threat
Field a squad where all members have at least two modifications (min. 4) and win the mission
Eradicate the infestation
Make certain of the new threat's location
Kill an elite enemy Medic with explosive damage in single player
Get a Soldier to have 5 modifications in single player
Kill an elite enemy Sniper with one of your own snipers in single player
Kill an enemy as it is psionically attacking you in single player
Kill a Muton Berserker in melee combat in single player
Eliminate all alien waves
Jump two stories in one move in single player
Use Collateral Damage to blow up a car in single player
Get at least 4 kills with XCOM Base Security personnel
Eliminate an enemy's shield and kill it on the same turn in single player
Beat a new special mission without losing any assets
Cause an enemy to suicide
Field a fully enhanced squad and win the mission
Augment a soldier in single player
Have your special-duty soldier kill three enemies in the same mission
Modify a soldier in single player
Stop a squad member from suffocating in single player