Here is the full list of all 27 Alekhine's Gun trophies - there are 8 bronze, 13 silver, 5 gold and 1 platinum.
Obtain all Trophies
Obtain 30 unique disguises in the game.
Use Chloroform on 30 enemies
Get 30 Headshots
Garrote 30 enemies
Hide 30 bodies
Obtain Maniac Ranking on a level
Complete game without killing except for assassination targets
Level 11 Completed
Level 10 Completed
Level 9 Completed
Level 8 Completed
Level 7 Completed
Level 6 Completed
Level 5 Completed
Perfect lockpicking attempt on a lock with at least 4 locking mechanisms
Level 4 Completed
Level 3 Completed
Perform a perfect rewiring during a sabotage puzzle
Complete a level using one disguise or less
Level 2 Completed
Complete all assassinations in a level using only accidents
Complete a Level without Killing except for assassination targets
Obtain Ghost Ranking on a level
Complete a level without using instinct mode
Complete a level without using your gun
Level 1 Completed