Here is the full list of all 20 Argonus and the Gods of Stone achievements.
Complete all Achievements.
Read all journal entries.
Set free the souls of all the Argonauts.
Set free the souls of all the isle's inhabitants.
Teleport to and from every temple on the isle.
Obtain every takable object on the isle.
Find all the broken pieces of wrecked ships.
Light all sconces and braziers.
Unearth a certain ancient skull.
Talk to every god on the isle.
Learn to use a forge.
Steal two things from their owner.
Find and place all the mosaic pieces.
Talk to five gods.
Talk to four gods.
Ride a stallion three times.
Raise the dead.
Talk to three gods.
Talk to two gods.
Talk to one god.