Great concept, but fix the controls
The concept is sound, but you seed to alter the controls somewhat: first, while I usually prefer arror keys for movement, WASD is better if the game involves using both the keyboard and mouse. It's more comfortable. Second, the "clear lines" button should be a little closer to the movement keys. As it is, I can't clear the lines without coming to a complete stop, leaving me vulnerable to the spiked ball.