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Hard Sudoku
For solvers who want a real fight. Hard puzzles hold back their clues, so single-cell logic only gets you so far — you'll need to spot pairs and chains to break them open.
Play Hard Sudoku free →What makes a Sudoku "hard"?
On Playoku, difficulty is graded by the hardest technique a puzzle actually requires — not by how few clues it has. A hard board will stall your naked and hidden singles and force you into naked pairs and pointing pairs to make progress.
- Freshly generated hard puzzles every game, each with one logical solution.
- Pencil notes are essential here — toggle notes mode and track every candidate.
- Undo, redo and hints when a line of reasoning runs dry.
- Free, no sign-up, with auto-save so a tough board waits for you.
Sharpen your technique
Our Sudoku tips & strategies guide covers exactly the moves hard puzzles demand — naked pairs, pointing pairs and the X-Wing. Want an even steeper climb? Try Expert Sudoku. Prefer to warm up first? Drop to Medium or Easy.