Here is the full list of all 7 Chromatic Isle achievements.
Solve the Summer Puzzle.
Solve the Autumn Puzzle.
Solve every puzzle and restore the Chromatic Isle.
Everyone does that. Sounds like a river. (Turn on every sound in the fall puzzle)
Solve the Winter Puzzle.
Solve the Spring Puzzle.
You're a monster. (Activate every button on the drum machine)