Here is the full list of all 27 The Last DeadEnd achievements.
Bad ending was chosen
Positive ending was chosen
Last enemy was defeated
Nagant found
All wall texts were read on "Maiden Tower" level
Dark sinner was defeated
50 headshots were made
Cyclop was defeated
Drudj was defeated
Shotgun found
Gulyabani was defeated
10 enemies were killed by Axe
10 headshots were made
10 enemies were killed by Makarov
Killing via auxiliary subject
The whole encyclopedia became available
Many enemies were killed by explosion
10 enemies were killed by Nagant
10 enemies were killed by Shotgun
10 enemies were killed by Sword
100 headshots were made
All wall texts were read on "Alleys of Old City" level
All wall texts were read on "Catacombs" level
All wall texts were read on "Shirvanshahs' bath houses" level
All wall texts were read on "Sabail Castle" level
All wall texts were read on "Streets of Old City" level
All wall texts were read on "Road to the Maiden Tower" level