Sudoku

How to play

Sudoku fills a 9×9 grid with digits 1-9 so that every row, every column, and every 3×3 box contains each digit exactly once. Pure logic — no luck involved. Wuti Zone's Sudoku ships with four difficulty tiers, conflict highlighting, pencil-mark notes, and a built-in timer so you can chase your personal best every day.

Rules

• Fill the 9×9 grid with digits 1 through 9.
• Each row must contain every digit exactly once.
• Each column must contain every digit exactly once.
• Each 3×3 box must contain every digit exactly once.
• Pre-filled clue cells cannot be edited.
• There is exactly one valid solution per puzzle.

Strategy tips

• Scan rows, columns, and boxes for cells where only one digit is possible (a naked single).
• Look for hidden singles — digits that can only legally go in one cell within a row, column, or box.
• Use pencil-mark notes to track candidates in harder puzzles; remove candidates as you place digits.
• Naked pairs/triples: when two cells in a region share the same two candidates, those candidates are eliminated from the rest of the region.
• For Expert puzzles, learn X-Wing and Swordfish patterns to crack cells that pure scanning cannot solve.

FAQ

Is Sudoku free?

Yes — every difficulty, every puzzle, free, no signup, no download.

How are difficulties chosen?

Easy 35-45 clues, Medium 30-34, Hard 25-29, Expert 22-24. Each tier guarantees a single valid solution.

Does my time save?

Yes. Your best completion time per difficulty is stored in your browser's localStorage.

Can I play on mobile?

Yes. Tap a cell to select it, then tap the digit button. Pencil-mark mode toggles notes.