I like the concept that you are up against someone and have to play a 4 lane rhythm game because of a ping pong match.
Some things that I suggest are making a lot easier difficulties, I think right now the map is pretty hard and also pretty unforgiving, so if you consider people that are newer to rhythm games maybe you could make easier difficulties or songs so that they don’t have to struggle as much.
Additionally, killing the player after just 3 attempts at hitting notes is too harsh so maybe you can have more lives or just have it impact your overall score at the end.
In any case, the idea of the game was interesting, it could very well be expanded on with more levels.