very cool game, reminds me of a mobile game i played before called beat craft, which also had this idea of using youtube videos for the charts lol. I think the game could allow a bit more customization, like making the notes be even faster than 2x, and making a difficulty above extreme (as an actual rhythm game player, the extreme mode with max speed still was too easy for me lol). I also noticed that the notes doesn't really care with the melody of the song, and always spawned at fixed intervals, regardless even of the song bpm (i checked camellia songs and even extratone songs, and yeah, i expected the charts to be harder, but it didnt...). I got pretty suprised when i pulled some of my songs (used a channel with very few subs), and the game actually found my videos lol. Last thing, for 4k rhythm games like this, i think that putting the keybinds to press the notes being DFJK instead of arrows is better. Hard to explain, just make the test and you will see why