Fun until level 90 and up. At that point there's way too many hidden blocks, causing it to be random luck instead of a puzzle. Only way to get past without starting the level over 4-9 times is to use coins, of which I have limited supply. And no, I ain't buying any. Since I don't know what's behind the hidden blocks, I have to click them at random and hope a block appears that can be used to erase three of the blocks taking up room in my hand. It's annoying.