Add two additional levels of stars and feature to filter songs on them
There are 2 things I miss when learning and exercising on the songs I already played. I can't see which songs I played on the highest score (all notes in time) and which songs I played on the highest score in one try from the beginning to the end correctly.
So maybe there would be good to have:
Additional star level "diamond" for playing all the notes in the song "perfect" in time.
Additional marker/star for the songs played all the notes in the song perfect in time in one take.
Add the filtering to master the songs to receive "diamond" stars and another to perform the song perfectly in time in one take.