Have you ever played Yoshi's Cookie? It's a fast-paced action game where you have to match up rows and columns of cookies to clear the screen. It also has a puzzle mode where you only have a set number of moves.
What about Tetris? You should know that by now; it's a puzzle game where you have to put various tetrominoes (four-square pieces) together to form complete lines.
What do they have in common, you ask?
Well, the creator of Tetris was a Russian mathematician, Alexey Pajitnov. If you read the blurb in Tetris Worlds, it gives a brief background behind the game, that he had a Russian computer writing with Pascal and no graphics. It became an instant hit and is still going strong today. He also endorsed another game called Clockwerx, but that's another story. If you're interested, go to an abandonware site (I recommend The Underdogs) and get a copy of it.
But it's a little known fact that Pajitnov also designed the stupidly hard puzzles for Yoshi's Cookie. Which explains why they're so tough! Or at least, why -I- find them hard. Don't believe me? Check This Out, it's a screenshot from the credits for Yoshi's Cookie.~Darkmark