Here is the full list of all 38 Styx: Shards of Darkness achievements. It takes around 25-30 hours to unlock all of the achievements on Windows.
Unlock all achievements
Unlock Gold level for all Insignias in all missions
Unlock all skills
Kill all the enemies in a zone
Push 10 enemies over the edge
Dissolve 10 enemies (vial of acid)
Teleport 20 times into a clone (with the skill)
Kill 5 guards with acid traps
Being invisible in a chest and not being caught by an enemy on a search
Be saved by a Life-saving Clone
Give of yourself to the worship of Lyssril...
Drink 25 vials of amber
Kill an enemy in his sleep
Create 50 clones
Unlock Gold level for all Insignias in a mission
Finish a mission with the gold Insignia of the Thief
Finish Mission 9
Finish a mission with the gold Insignia of Swiftness
Craft 30 items
Finish Mission 8
Finish Mission 7
Finish a mission with the gold Insignia of the Shadow
Finish Mission 6
Finish a level without taking damage
Unlock your first ultimate skill
Remain invisible for a total of one minute
Finish Mission 5
Pickpocket 10 enemies
Finish Mission 4
Finish Mission 3
Finish Mission 2
Complete a level without using an amber power
Finish Mission 1
Collect 50 raw materials
Finish the introduction
Finish a mission with the gold Insignia of Mercy
Having hidden 50 times in a duct or a hideout
Get out alive from 10 red alerts