Quick tips
- Start with the row or box that already has the most digits.
- Use Notes for candidates. The large digit is the answer.
- Undo as soon as a placement crowds the row.
Sudoku Daily
How to play
Fill every row, column, and 3×3 box with the digits 1–9, once each. Given numbers stay put. Notes, Undo, Erase, and Hint sit on the board.
About this site
Free in the browser. No account and no install. Continue Last Game reopens the board you left, in this same browser.
Guides
Short explanations of the rules and the techniques the game expects you to use. Read one, then return to the board.
Rules
What each row, column, and 3×3 box is allowed to hold.
Notes
Pencil marks, when to add them, and when to clear them.
Singles
Naked singles and hidden singles, with a worked row.
Killer cages
How a cage sum works on top of ordinary Sudoku rules.
Continue a game
Daily Challenge and Continue Last Game stay in this browser.
Common mistakes
Repeated digits, stale notes, and the three-mistake setting.