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