Here is the full list of all 26 Lunacid achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Find the Second VHS Tape
Unlocked all of Etna's alchemy recipes
Wake the Old One
Reached the Ruined Arena
Reach Level 75
Reached the Prison
Reach the Castle
Reach Level 50
Slay an Abyssal Demon
Reach the Sewer
Reach the Lake
Reach the Catacombs
Reach the Forest
Reach Level 25
Reach the Grand Library