How to play Sudoku
The goal of Sudoku is to fill a 9×9 grid with the numbers 1 to 9. The grid is divided into nine 3×3 blocks, and the rule is simple: every row, every column and every block must contain all nine digits without repeating any.
In Grafito, select an empty cell and type a number with your physical keyboard or tap the digits on the on-screen keypad. If you make a mistake, the conflicting cells are highlighted so you can fix them. Every game is generated instantly with a backtracking algorithm that guarantees a valid solution, so you never play the same board twice.
Sudoku rules
- Every row of 9 cells must contain the numbers 1 to 9 without repeating.
- Every column of 9 cells must contain the numbers 1 to 9 without repeating.
- Each of the nine 3×3 blocks must contain the numbers 1 to 9 without repeating.
- The numbers given at the start (the clues) can't be changed.
- The game is complete when the whole grid is filled and there are no conflicts.
Tips & strategy
- Start with the rows, columns and blocks that already have the most numbers: that's where you'll find cells with a single possible answer soonest.
- Use the 'single candidate' technique: if only one number fits a cell by elimination, place it with confidence.
- When you get stuck, note the candidates for each cell (mentally or with the hint) to spot pairs that remove options from the rest of the block.
- Don't guess: a well-formed Sudoku always has a logical move. If in doubt, look for another area with more information.
- Keep the timer running only when you play seriously: your best times per level are saved as records.
FAQ
How do you play Sudoku?
You fill a 9×9 grid with the numbers 1 to 9 so that none repeat in any row, column or 3×3 block. You start from a few clues and complete the rest by logic.
Is Grafito's Sudoku free?
Yes, completely free and with no game limit. You don't need to create an account or download anything: it plays right in your browser.
Do all sudokus have a solution?
Yes. Every board is generated from a valid, complete grid with cells removed, so there is always at least one solution.
What's the difference between the levels?
The level only changes how many cells start empty: 36 in easy, 46 in medium and 54 in hard. The more empty cells, the more technique you need.
Can I play Sudoku on mobile?
Yes. The grid and on-screen keypad adapt to small screens, so you can play on phone, tablet or computer.
Are my records saved?
Yes, your best times per level are saved in your own browser. They are never sent to any server.