Play Hard Sudoku Online
A free hard Sudoku puzzle with only 25 starting clues. Expect long deduction chains, hidden singles and pairs, and the occasional X-Wing. A genuine challenge for experienced solvers.
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Scan with your iPhone cameraFrequently Asked Questions
How hard is a hard Sudoku puzzle?+
Our hard puzzles start with just 25 of 81 cells filled. The low clue count forces advanced techniques — hidden singles, hidden pairs, pointing groups, and sometimes an X-Wing — rather than simple scanning.
How long does a hard Sudoku take?+
Experienced players typically need 20 to 45 minutes. There is no shame in longer — hard puzzles are designed to make you hunt for the next logical move.
What should I do when I get stuck on a hard Sudoku?+
Re-scan for hidden singles first — they hide behind cluttered notes. Then look for naked and hidden pairs, then pointing groups. If the grid is still locked, hunt for an X-Wing. Never guess: every puzzle here is solvable by logic alone.