It's been a while since I saw a legit rhythm game in a game jam. I think the idea is quite unique and matches the gameplay nicely. The game is quite nicely done, and I see some potential in the game of being a well-rounded product. The song choices are nice, though I don't really like songs with no clear beat at the start. Throws me off every time. I managed to get two full combos during the short period of playing, and I'd say I quite enjoyed it.
For some issues, I think the shrinking square is not quite enough to determine the perfect timing, and leaves much to guesswork (pairing with no clear beats makes it a bit annoying). maybe also adding a fast effect alongside the slow square will help, but I am not certain. I would also point to the fact that without SFX when hitting the beat, it worsens the situation even more. There is also a minor issue that the song "neon flames" has the opening notes starting at around a second or so, which is a bit too early for the player to react. And why is the girl not on the dancing floor? Why!
Anyway, I quite enjoyed the game. Good job!