Loved the Gameboy intro jingle! The soundtrack and graphics were perfect.
You've really nailed the Gameboy aesthetic—there’s a great old-school vibe to the whole experience. I can see a lot of passion behind it! That said, I found it a bit challenging, even for someone who loves a good test of skill.
I noticed some progression quirks: starting at level 16, beating the boss, and then getting an instant gameover felt a bit jarring (and the message made it seem like I could have done something to 'collect the wish orbs' like they instructed, but I don't think I saw any..). When I select continue from the main menu, it took me to level 17, but it was really intense! So much was happening so quickly, and I found it hard to react. Maybe toning down the intensity or giving players a LOT more shielding could help everyone fully experience the awesome content you've created.
Overall, great job on the execution! A little extra balancing and playtesting could really make it shine. Nice work!