RKF

RKF, or Rhythmic Kicking Firehead, is a shooter mixed with a rhythm game. You don't actually have to do anything in time with anything - the game automatically fires for you, and its firing sets off drum sounds. An ever-increasingly intense wall of black circle things comes towards you, which you must shoot to eradicate.

At the end, the number of verses multiplied by the number of circles you killed makes up your final score.