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