Leap: Knight Tour Puzzle

One piece. One rule. You may only move the way a chess knight moves. The goal is simple until you try it: cover the whole board, landing on every square exactly once. Thirty-six squares on 6×6. A hundred on 10×10. The difficulty is not finding a move. It is not walling yourself in twenty moves before the end — when the board still looks open and the way out is already gone. A thousand-year-old puzzle, by the way. Al-Adli wrote solutions down in 9th-century Baghdad; Euler took it to the Berlin Academy in 1759. THREE MODES Apprentice — every reachable square shows how many moves would be left from it. Not the answer: a way to learn to see the tight places. Regular — reachable squares are simply marked. Prodigy — no hints at all. FIVE BOARDS From 6×6 to 10×10. A smaller board is not an easier version but a different problem: there is less room to be wrong. STEP BACK A mistake can be…