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