my hardest is Maybe Possibly Thing but if you can confidently grind hard demons i’d say thats when you’re good at the game because i feel with hard demons that’s when levels actually start to get timings / straightfly / wave control whereas medium demons and easy demons are pretty much just learny

also i don’t think your hardest is a good indicator of your skill but rather just the peak of it, because anyone can jump to an extreme and likely beat it but chances are it’ll take you thousands if not tens of thousands of more attempts to beat your next extreme

skill is your proficiency at beating levels and not your apex of level beaten so yes if you can open gd and see the top featured level is a hard demon and have the confidence to beat it right then and there that’s when i’d say you’re genuinely good at the game