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# The Most Devious Riddle In Chess Becomes An Addictive iOS App

## BoxPop turns one of the immortal game's most enduring puzzles into a game for everyone.

Chess is a game that is often used to express mathematical concepts of the infinite. Although each game takes place on only an 8x8 board, we've known since 1950 that there are more possible chess games than atoms in the known universe. But even far more mundane chess problems have mathematically staggering answers. Consider, for example, the Knight's Tour—a classic chess puzzle in which a knight must move to each square on the board only once—has 26.5 trillion possible paths to choose from, depending on where the knight starts.

Thanks to a new iOS app, the Knight's Tour has now broken free of the chess board to become its own cleverly designed puzzle game. Developed by iOS developer FreshPlanet, BoxPop invites players to conduct a Knight's Tour on an ever-changing series of grids, popping boxes as they land on them. Using the movement pattern of a knight, the player needs to explode each square on a grid, with no doubling back or do-overs.

Luckily, since the Knight's Tour can be a particularly tricky math problem—as a kid in Chess Club, the only way I could solve it was by rote memorization—BoxPop doesn't require you to fully solve each puzzle. Instead, there's an Angry Birds style three-star system which ranks you according to how close to the optimal solution of each board you get. In addition, not all BoxPop boards are symmetrical: unlike a rote chessboard, some configurations are horseshoes, circular, triangular, and more.

But even in purely symmetrical configurations, BoxPop can be astoundingly tricky. Unlike a Knight's Move on a regular chessboard, BoxPop's grids become as large as 10 x 10. That's the same Knight's Tour configuration, incidentally, that inspired French author Georges Perec's classic 1978 novel, Life: A User's Manual.

BoxPop is another sleek reminder that even when you don't know how to play it, chess is the ultimate game. You can download it free from the iOS App Store here. And need some tips? Just remember Warnsdorff’s Rule.