Thanks for your feedback. I've been updating it some since the rating began and it will be updated at Itch when the rating period is over. <P> can be pressed to re(P)lay the current level or press <BackSpace> can be used to totally restart.
In later levels, Blue balls move a platform one direction, and Green balls move platforms in the other. Also Green walls are destroyed only by green balls, blue walls are destroyed only by blue balls.
In an updated version that I have already updated, there are numerous Keys and Doors (walls) that only open (break) if you have that particular key.