Here is the full list of all 13 Way of Rhea achievements.
Solve one level's worth of puzzles.
Solve all puzzles in Shrew's Biome.
Solve all puzzles in the the Ice Biome.
Solve all of the puzzles in Rhea's Biome.
Solve all of the puzzles in Professor's Biome.
Solve all puzzles in Final Act.
Rescue little Hermie from the Ice Biome.
Steal a Sun Orb.
Steal an Earth Orb.
Steal a Water Orb.
Unlock the Dev Museum.
Use undo 100 times.
Get trapped by leaving Hermie's dad behind in the first Ice Biome puzzle.