The "menu.game" sound event is seemingly uncustomizeable now. It used to be able to be altered, with one's own preference for music, but now it is not.
I personally prefer to only listen to C418 music, being an old Beta miner myself. However, this forces me to listen to the newer music more often.
I have attached a prototype resourcepack for seeing this on display.
Add replace: true inside music.game. Not a bug.