Great game, but after around the 15-20 mark the game just stops getting harder. It could introduce some more prompts at that point, maybe even introduce that one complicated part near the end of the Rhythm Hell video
Edit: After a score of 70, I actually got a new polyrhythm I hadn't seen before! Basically, there's a triplet lasting a half-note composed of a quarter-rest then two eighth-notes then a quarter rest, then a quintuplet lasting a half-note composed of an eighth-rest and four eighth-notes.