The level design of this game really stands out to me. Each mechanic is taught well initially and the diversity of the puzzles is truly incredible, with each one challenging the player's knowledge of these mechanics with increasing difficultly (and with an increasing amount of dopamine upon figuring each puzzle out, some of the later ones felt sooo good to finish. Stretchier and Not Not were two of my favorites).
However, this game really stood out with its interesting methods to keep the player playing the game. Levels are each separated by the level selection area, a free-roaming space that acts as an extension of the puzzles of the area and what they represent. In the tutorial area, you get a simple, open space and a lock system that keeps you out of the next level. As you learn about each of the 2 apple types in their respective levels, you also get access to them inside the level selection area. This acts as a way for the player to test out the apples on their own and learn about it outside of the pressures of a level. This extends to the main area with all of the other puzzles, except instead of trying to teach the player or let them learn through trial and error, its trying to make them solve puzzles, which is reflected in the level selection area as the player is solving puzzles as a way of unlocking the big puzzle everything is contained in. In this way, the game constantly gives you feedback for getting better at the game; each time you complete a harder puzzle, you solve a piece of the whole game.
On a side note, it is equally impressive how the game departs so extensively from Snake Game, a pretty clear influence on at least the game's aesthetics. It basically turns everything that Snake Game is on its head; from a high score chasing game requiring quick decisions in non-stop gameplay where one touch means death, to a slow paced puzzle game that wants you to think about a situation as much as possible and encourages failure through trial and error. It allows for a fresh take on a familiar experience and is a truly amazing feat of design.