I'm not very creative, but I'd love a hard mode where the attacks have faster and/or more projectiles and you have to actually do the quiz, and for the lower part of the map, it could be like a horror-looking final boss with Miku trying to stop Teto from leaving with some eye-blob-thingy minions (to give a purpose to the attacks that damage all enemies).
But again, I know this is already so much work already and I still love this short fangame. I really don't want to take too much of your time. If anything, I'm glad a Mesmerizer fangame even exists, so thank you.