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