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