Nice Voltorb Flip clone, although it does lack some of the satisfaction of flipping tiles. Zero could use some sound effects/animations when clicking a tile for instance.
I also like the different difficulties, although often the easiest difficulty is either "you win" or "50-50 chance lose a life." I'm less admirable about the lives, the stakes are significantly lower when hitting a 0 doesn't make you lose. Imagine a Minesweeper with lives.