It is just off the screen, and when I click it, nothing happens. :c (I took a screenshot, went back to it... And now it works. I don't know what changed, but apparently we're good now.
Okay! I've played a round. The control scheme of moving, clicking, and also hitting the number keys on beat is kind of crazy! But I do enjoy that leveling up actually adds those things to the soundscape. :) very cool!