Kempelen's Impossible Board: A Century-Old Chess Puzzle Resurfaces

A hobbyist has built an interactive web version of a chess problem attributed to Wolfgang von Kempelen, the 18th-century inventor better known for the Mechanical Turk automaton. The challenge: position four black queens and one black bishop on an empty board such that every single square is under attack, leaving nowhere safe for a white king. It is a total-coverage problem with no margin — miss one square and the puzzle fails.

The site lets visitors drag pieces onto squares and remove them by tapping, turning a static historical curiosity into a hands-on solver. Kempelen reportedly used puzzles like this to needle the strongest players of his era, and the constraints make it genuinely hard: queens are powerful but their attack patterns overlap heavily, so finding a non-redundant placement that also leverages a bishop’s diagonals requires careful combinatorial reasoning.

The project is a small reminder of how lightweight web tooling can revive obscure intellectual artifacts. No login, no framework bloat — just a board, five pieces, and a problem that has outlived its author by more than two centuries.