Here is the full list of all 47 Operencia: The Stolen Sun achievements.
Place both skulls onto the coffin in the First Royal Tomb
Unlock the last tier of at least one talent tree
Complete Lake of Anna
Spend two minutes under water in Lake of Anna
Equip an item to all slots of a character
Unlock at least three skills from any talent tree
Level up a character
Win a battle
Complete Gate to the Underworld
Complete The Great Forest
Complete the First Royal Tomb
Complete Deva Fortress
Complete Bálványos
Complete World Tree
Complete Atop the World Tree
Complete Copper Forest
Complete Deep in the Copper Forest
Complete the Second Royal Tomb
Complete the game with any difficulty settings
Get the secret treasure of the Hungry Plant in The Great Forest
Open the skeleton's tresure chest in Deva Fortress
Reveal the secret chest in Bálványos' block room
Force all mouths to close at least once in World Tree
Use up all the cheap wine in Atop the World Tree
Unlock and use the Copper Forest's workshop door from the inside
Get the treasure from the well in the Copper Forest
Find "Letter to Olek" in Gate to the Underworld
Levitate twice in the Second Royal Tomb
Try to remove the channeling crystal after it was activated in the Glass Palace
Fully reveal all maps
Buy any equipment from Elia
Buy everything from Elia's stock
Brew all potions
Complete the game with at least two difficulty settings switched to hard
Reveal all secrets
Dig up all buried treasures
Open all locked chests
Reach the highest level with all characters
Pile up ten pieces of Firewood
Defeat all enemies in the game
Unlock everything on two talent trees for at least one character
Defeat an enemy group with one hit
Find all recipes
Equip a full armor set on any character
Reach 220+ on all three main battle stat at the same time
Discover all campfires