About Sudoku Online
Sudoku with four difficulty levels plus variants such as X-Sudoku, Windoku and Killer Sudoku. No sign-up; puzzles load straight in the browser.
How to play
- Fill the 9x9 grid with digits 1 to 9.
- Each row, column and 3x3 box must contain every digit once.
- Variant modes add extra rules, such as diagonals or cage sums.
Tips
- Use pencil marks to note candidates in each cell.
- Scan for a digit that can only fit in one place in a box.
- Start on Easy to learn the patterns, then move up a level.
Good for
Classic number logic at any skill level.