On the other phone, open this same page and tap Join as controller, then enter this code.
A webcam beside the projector that sees the whole floor. The page finds the kids itself and the floor answers to their feet. Nothing leaves this device.
Enter the code shown on the device running the game.
Pick once — it stays that way until the page is refreshed.
Nine tracks from OpenGameArt.org, shuffled for every new game. Each one was loudness-matched and converted to AAC for the web.
Whose birthday is it? Their name goes on the scoreboard, and winning ends in a birthday parade: the birthday song, and their name in lights. It switches itself off tomorrow.
Cast this screen to the projector, then tap Go. It runs itself from there.