This game's just really cozy and adorable! I love the palette and concept and the simple yet beautiful spritework. I would definitely play this on a real gameboy! Though honestly, I went in blind, so it felt like half the puzzle was navigating to the right spots. XP The controls are rather unintuitive - once I looked up how they worked (after beating the game) it got easier, but they still feel fiddly and I have to consciously remind myself how they work.
Unfortunately, on level 8 of endless mode I alt-tabbed to answer something on Discord, and clicked outside the game window when returning ... after which I couldn't re-focus on the game at all! No amount of clicking on it, pressing keys, or trying to tab back into it got the game to respond, so that's an issue you might want to look into?