Okay so, I was thinking about it for a bit and I think it would be cool to implement some type of mode where you could sing since so for you've added Taiko, Osu! mania, Osu! its self, and catch the beat, but a singing mode would be pretty cool in my opinion. I think it would be cool and it would allow people to do something different in the game. Though I understand this wouldn't be easy to implement, and if it were to be added it would take awhile to implement.