Need a few opinions on this mechanic in my game

ive had this idea of a rhythm type game for a while now, but i’m not sure how i could implement the core gameplay mechanic for it.

I’m not sure if anyone has already done this or not, but I haven’t seen any rhythm games attempt this so… My idea for it is that its your usual rhythm game, but you aren’t limited to any specific rhythmic boundaries and can experiment with your creativity. Its easier to show on an example:

Imagine something like undertale, where its a 1 on 1 battle against an enemy, but you wield the drums. you have an ability called “drum fill”, which when used, would start up a sequence where you have to be creative and do the best drum fill possible, the internal logic would then “rate” your sequence of kicks hats and snares, and apply damage to the enemy based on how creative and how well you’ve played a drum fill, while not repeating the same pattern you’ve used the last time you used this ability. I was thinking of maybe letting AI grade it based on some prompt like “rate this drum fill, E minor key, 140 bpm, K-H-|S-H-|H-H|SSSS| on a scale from 0.0 to 10.0”, where K represents a kick, H a hat and S a snare, im not sure it will be able to process information at face value when prompted this way. I also had thought of another way to check if the drum fill actually makes sense and is, in fact, a drum fill - is to store pre-defined patterns, that if dont align, would mean its not really a good one, but the sheer amount of drum fill pre-defined patterns needed is insane, especially if its focusing on the player’s creativity, since they can still play a banger fill and get no points whatsoever just because i haven’t thought of that one.

And thats just drums, i was also planning on having the guitar “weapon” where you could play a solo of some sorts, anyway i’d like to hear you guys’s opinion on this and how would you do it?

If you are able to design a system that rates the drum fills in a way that feels “fair” to the player, I think it is a good idea! It could also lead to “drum battles” with enemies, where the AI rates the drum fills and decides who wins each round, just like a rap battle or something similar