Interesting mechanics. I just hope the rythm dots - whatever you call it - is at the middle with a bit of fading opacity at the sides. Or put it above character. The point is to see the upcoming rythms instead of constantly looking down.
The rifle is also a joy-killer, why the hell does it overheat so fast and what is the point of preventing player to stop shooting for a while? This would just be a burden, an extra thing to monitor constantly. I suggest to remove it and see how playtesting feels lighter because you got lesser stuff to worry about and focus on the fun elements: shoot on rhythm, and avoid enemies.