i have created a OSU type game with python pyqt5 , the special thing about is it have invisible background so you can play while working or in boring part of your work , also you can set youtube link on the game to play , you can customize a lot of thing and import export setting .Also there is fps osu, I am not sure is this correct place to talk about it or not. maybe you will find it interesting . its free and open source
https://gitlab.com/krafi/inviOSU
https://gitlab.com/krafi/inviOSU