Specifically for kids aged 5-9 and has no need for an account. We will play a nursery rhyme, kids movie or show tune, or a song they've likely learned in PreK through 2nd grade and they have to finish the next logical phrase or stanza. If they get it right, the song continues and they win that round. After 6 songs, they can earn badges and are ranked with all other users that day but only if they do well. I've had a load of fun playing it myself while building it and I bet your kids will too!
Also built to tolerate the chatter that often accompanies the excitement of the song played or the screeching that comes with getting it right or wrong.