The philosophy of this game is lovely. The title screen says it outright: play whatever you want, what matters is keeping time, and if you want extra points try to stay in key, every song is in C major / A minor so just avoid the sharps. Just vibe man. A rhythm game that gives you freedom instead of punishing you is a beautiful design choice, and it's the opposite of what the genre usually does.
The drawn keyboard map on the title screen, with each key labelled with its note, is the best possible way to explain that. I understood the instrument in about five seconds.
The band scene is great: red theatre curtain, Bassa in a red dress with the bass, a trumpeter in a blue suit and sunglasses, a guy in a hat on bongos, and an actual audience of five people drawn in front of the stage. It gives the gig real life. The HUD is clean too, Score, Combo, and a constant reminder of the key so you don't wander off the scale. Three tracks with names that suggest progression is a good structure.
Caveat on my score: the problem here is on my end. A rhythm game depends on hitting keys at the exact moment and my inputs come out delayed, so I finished on 0. That says nothing about your game, and you'll do infinitely better than I did.
What I can fairly comment on: the blue note bars scrolling across are thin and close in colour to the purple background, so reading the rhythm visually is hard. Much higher contrast (yellow, white) would help a lot. And there's no countdown before the song starts, so you're already behind on the first beat.
Also, posting the full Godot project as a zip alongside the game is exactly the right answer for this jam.