Full list of all 26 Alekhine's Gun achievements worth 1,000 gamerscore. It takes around 12-15 hours to unlock all of the achievements on Xbox One.
Complete Level 1
Complete Level 2
Complete Level 3
Complete Level 4
Complete Level 5
Complete Level 6
Complete Level 7
Complete Level 8
Complete Level 9
Complete Level 10
Complete Level 11
Get 30 Headshots
Use Chloroform on 30 enemies
Perfect lockpicking attempt
Perform a perfect rewiring (sabotage minigame)
Garrote 30 enemies
Obtain all disguises in the game
Complete a level using one disguise or less
Complete all assassinations in a level using only accidents
Complete a Level without Killing (except for assassination targets)
Complete game without killing (except for assassination targets)
Obtain Ghost Ranking on a level
Obtain Maniac Ranking on a level
Complete a level without using instinct mode
Complete a level without using your gun
Hide 30 bodies