Version Two I guess

Upon some feedback, I decided to make some improvements. This is not a comprehensive list, as many of the changes were very small tweaks or bug fixes. The most notable changes are:

Added brick durability, indicated by colors.
Three times as many brick layouts for levels: 15 instead of 5. Additionally, looping of levels will increase brick durability in layouts.
A bunch of new powerups, with one paddle powerup and one ball powerup being available at the same time. New powerups of the same type will replace the old one.
Some tweaks to the difficulty curve to account for requiring multiple hits for each brick.

I don't plan on doing additional development for this game, but if there are any significant bugs or small adjustments that could significantly improve user experience, I might make a patch or two. Regardless, I welcome all feedback, good or bad.