Very cool. Also very difficult to play in real time on a phone screen.

This is a neat idea. Splitting one guitar across phones via QR is something I have not seen before. The miss-a-note hole in the song is a clear shared fail state, which helps the group feel it together. On the playability side, fuzzzerd is right that timing on a small phone screen is harsh; a slightly wider hit window on the first song, or a short practice pass before House of the Rising Sun, might help rooms actually finish a track. Curious whether latency between phones is noticeable when someone is on mobile data.