Here is the full list of all 36 TUNIC achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Found Secret Treasure #2
Found Secret Treasure #4
Found Secret Treasure #10
Found Secret Treasure #12
Found Secret Treasure #11
Found Secret Treasure #5
Found Secret Treasure #8
Completed the Manual
Found Secret Treasure #7
Found Secret Treasure #6
Found your rightful place
Found Secret Treasure #9
Restored corporeal form
Freed a friendly fairy
Found Secret Treasure #1
Found Secret Treasure #3
Earned the Cathedral's Prize
Completed key collection
Found the blue key
Found the red key
Chopped down 1000 blades of grass
Understood the margin of page 17
Found the green key
Engaged a strange device
Rang the Western Bell
Perfectly executed a special technique
Made a wish
Froze yourself
Made an offering
Rang the Eastern Bell
Found a sword
Was resurrected
Found a stick
Had 10 moneybanks at once
Made 15 wishes
Found a certain weapon before getting a sword. (Page 38)