HUGE fan of rhythm games, I really like this! It reminds me of Spin Rhythm DX and DJ Hero quite a bit(and a little bit of Beatmania). I wish there was a calibration option and a little more feedback(like a note sfx option), but other than that this is a pretty solid foundation and I would love to see this become a full game. I really like the songs, too. I'd recommend making the blue and orange notes more recognizable on which one to press, like a shape change or the orange and blue being on separate sides kinda like Sound Voltex if that makes sense.
There being a chart editor available is also very impressive! Also is the cat's design inspired by 808 from Hi-Fi Rush? Lol