Can you over-exercise your brain? Well, I certainly know, after trying this, that your brain can hurt from too much thinking. This game has to be the hardest puzzle game I have ever played, and I still can't get past level 17 (and level 14 and 15 for that mater, there are some secrets to skip a few levels (which I still try to complete though, no point in skipping puzzles in a puzzle game)). It is also highly addictive. It took me 17 levels to break my addiction, and then it was only because the puzzles got too tough.