Sudoku
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About Sudoku
Sudoku is the familiar number-placement puzzle on a nine by nine grid. Each row, each column and each of the nine three by three boxes must end up holding the digits one to nine exactly once. Every puzzle here is generated fresh and has a single solution, so you can always get there by logic instead of guessing.
You choose Easy, Medium or Hard, which leaves 40, 33 or 27 starting numbers. Allow about five to twenty minutes. A good game is a clean one: few mistakes, no hints and a steady pace, because all three affect the final score.
How to play Sudoku
- Pick a difficulty on the start screen and wait a moment while the puzzle is generated.
- Select an empty cell. The row, column and box light up, and matching numbers are highlighted.
- Enter a number with the keyboard or the number pad. A wrong number turns red and costs one of your three lives.
- Switch Notes on to pencil in small candidate digits instead of final answers, and use Erase to clear a cell.
- Fill all 81 cells correctly to finish. Three mistakes end the game.
Controls
| Keyboard and mouse | Click a cell, then type 1 to 9 to fill it. Use the arrow keys to move between cells, Backspace, Delete or 0 to erase, and N to switch pencil notes on or off. |
|---|---|
| Phone and tablet | Tap a cell, then tap a number on the pad under the grid. The Notes, Erase and Hint buttons sit below the pad. |
Scoring
A solved puzzle starts from a base of 1000 on Easy, 2000 on Medium or 3000 on Hard. It then loses 1.5 points per second, 100 per mistake and 150 per hint, with a minimum of 100. If you run out of lives, you only receive 5 points for each correct cell you added yourself.
Tips and strategy
- Scan for digits that already appear many times. If a number is in eight places, the ninth cell is nearly always forced.
- Look at each box and ask where a specific number can go. Often only one cell in a row, column or box can hold it.
- Use Notes for cells with two or three candidates, then clear them as you place numbers. The game removes related notes automatically.
- Mistakes are checked instantly against the solution, so avoid guessing. A wrong digit costs a life and 100 points, far more than a slower think.
- A hint fills a correct number but costs 150 points. Use it when you are truly stuck and would otherwise waste minutes of score on the timer.
Sudoku FAQ
▸Does every puzzle have only one solution?
Yes. The generator removes numbers only while the puzzle still has exactly one answer, so pure logic can solve it without trial and error.
▸What counts as a mistake?
Entering any digit that is different from the solution for that cell. It turns red straight away and uses one of your three lives.
▸Which difficulty should I start with?
Try Easy first, which keeps 40 numbers on the board. Hard leaves 27 and has a higher base score, but it needs more advanced scanning.
▸Why are some number buttons greyed out?
A digit's button is disabled once all nine copies of it are correctly placed on the grid, so you can see which digits are still needed.
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