Here is the full list of all 14 The First Tree achievements. It takes around 4-5 hours to unlock all of the achievements on Windows.
Finish the game
Find your name again in a familiar place
Uncover all secrets and discover a priceless treasure
Collect all 150 stars
Find all 5 secret items
Uncover all main items in the game
Collect 100 stars
Activate all of the obsidian rocks and unlock the way
Find your name
Collect 50 stars
Reveal the king of the rabbits!
Catch your first bunny
Find a secret item
Dig up your first item