I really appreciate you packaging an emulator with the download because I don't know that I would've gone out of the way to get one myself. I think the core concept is really good but it would've been nice to see the ideas pushed a bit further so there was some difference between red and blue enemies, or maybe additional enemies that are only red or blue. And I don't know the limitations of the Master System so it might not have been possible, but I would've liked some kind of background music or ambient sound (though the sound design in my game was a bit lacking so I can't judge you too harshly for that).
But congrats on making a Master System rom! There aren't many people who can say they've done that.