How to play Sudoku
The board is a 9×9 grid split into nine 3×3 boxes, partly filled with starting numbers. Fill every empty cell so that each row, each column and each 3×3 box contains the digits 1–9 exactly once. Every puzzle here is computer-generated with exactly one solution.
Controls
- Click or tap a cell to select it, then press a number on the on-screen pad or your keyboard.
- The starting numbers are shaded and can't be changed; clear your own entries with ⌫ or Backspace.
- If a number clashes with another in its row, column or box, both highlight in red.
- Pencil mode (the ✏️ button or P) lets you pencil small candidate digits into a cell; entering a final answer clears the notes in that cell and removes that digit from its row, column and box.
Tips
- Look for cells where only one digit can possibly fit, and rows/boxes that are nearly complete.
- Pick Easy to warm up, then work up through Medium and Hard to Expert, which starts with the fewest clues.
- On harder boards, use pencil marks to track candidates — it's how experienced solvers crack the tough cells.
More brain teasers: try Lights Out or Minesweeper, or see all games.