Here is the full list of all 18 Baba Is You achievements. It takes around 25-30 hours to unlock all of the achievements on Windows.
Complete the space area.
Complete the forest.
Beat the game.
Complete the forest of fall.
Complete the ruins.
Complete the solitary isle.
Complete the lake.
Complete the cavern.
Complete the mountain.
Complete the abstract area.
Complete the garden.
Complete a secret area.
Find an orb.
Complete the world map.
Really beat the game.