I certainly wasn't thinking you'd completely mold together a mode from stuff in this thread 
Anyway, as I see it, there are two ways to mix rhythm with the bullets...
first of all, making the bullets spawning at the time the beat would be clicked...
secondly, locking y position and having the bullet/set of bullets match your y position at the time the beat would be clicked...
Certainly, since the bullets will be made from an existing beatmap as opposed to a custom bullet pattern, it definitely needs to be considered how it will be made intricate and require a lot of skill to pass a map like... well anything DJpop made's hardest difficulty... without it being impossible (well DJpop's maps are impossible but you know what I mean
)...
Hmmm, I've assumed a non-shooting run style of play, I guess having the player shooting or not having it would make a huge difference to gameplay...
NachoPiggy, I think it would most definitely be better to keep it as simple as is reasonable and such a sound based idea would perhaps be a bit hard when you are trying to dodge the kind of heavy bullets one expects in Bullet hell games
I think just plainly getting shot at and dodging, getting points through that somehow and the better you dodge the more points you get bla bla bla...

Anyway, as I see it, there are two ways to mix rhythm with the bullets...
first of all, making the bullets spawning at the time the beat would be clicked...
secondly, locking y position and having the bullet/set of bullets match your y position at the time the beat would be clicked...
Certainly, since the bullets will be made from an existing beatmap as opposed to a custom bullet pattern, it definitely needs to be considered how it will be made intricate and require a lot of skill to pass a map like... well anything DJpop made's hardest difficulty... without it being impossible (well DJpop's maps are impossible but you know what I mean

Hmmm, I've assumed a non-shooting run style of play, I guess having the player shooting or not having it would make a huge difference to gameplay...
NachoPiggy, I think it would most definitely be better to keep it as simple as is reasonable and such a sound based idea would perhaps be a bit hard when you are trying to dodge the kind of heavy bullets one expects in Bullet hell games
I think just plainly getting shot at and dodging, getting points through that somehow and the better you dodge the more points you get bla bla bla...