It is a great game except once you have completed many of the puzzles it gives you the same few puzzles over and over. This is despite there being hundreds of puzzles to rotate through. These are the mystery levels. The app gives you old puzzles again, which is fine but there seems to be a glitch and the app ends up giving you the same old puzzles over and over and doesn't seem to rotate through all the puzzles that are available. It would be nice if it used all the old puzzles