Hard Sudoku X Online
Free 9×9 Sudoku X at hard difficulty — fewer givens, diagonal-led deductions.
00:00
Playing as a guest? A free account unlocks ad-free play, XP, streaks, and the leaderboard.
Play ad-free — track every solveAll-time top players
All-TimeHard Sudoku X stretches the technique repertoire you've built up on classic. With 22–25 givens, you'll need hidden pairs, naked triples, X-Wing, and diagonal-aware versions of the box-line family. Sudoku X has its own technique cluster — X-cycle on a diagonal, pointing pair across a diagonal — that you only meet at this tier. Every Hard puzzle on Sudoku247Online is verified uniquely solvable by pure logic; the diagonal constraint never forces a guess, it just makes the deduction shorter.