Thanks so much for the kind words, and very happy you took notice of the levels.
The levels are handcrafted, and I made 9 of them (3 for each world). Originally, there was supposed to be 15 but making each stage took so long. Running it over and over again to make sure its balanced, and that the difficulty scales fairly, that I couldn't just squeeze them in :(. Also, my wife would have had to make 2 more backgrounds lolol