I like the commitment to your aesthetic! I will say that "Press Any Button" didn't work for me until I reset the cartridge. I also thought something was broken in the intro sequence since it took so long for my Mamabot to say anything. I would be a bit more explicit about the controls -- given that they are simple, they could be taken care of on the title screen or in the text field under the embedded game.
I would definitely add more levels to make the difficulty curve a bit less steep. I ended up skipping the last level, and I wished there had been more to play after it.
Over all, though, great job!