Open it on a laptop or a TV and host a room; every phone scans the QR and gets its own strings of one guitar. Tap a dot when it reaches its ring and the big screen plays your note; miss it and the song has a hole. Two phones split the guitar in half, four make a band of thumbs. The first song is House of the Rising Sun.
Free, no account, and it plays alone too. I’d love to hear where it falls apart with real friends.
Very cool. Also very difficult to play in real time on a phone screen.