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