Sudoku

Sudoku is a free online logic puzzle you can play instantly in your browser, no download or account needed. It follows the classic rule: no repeated digit in any row, column, or 3x3 box, on the full-size 9x9 grid that newspapers and puzzle books have run for decades. Tap a cell, then tap a number to fill it in; wrong digits are flagged immediately so you always know where you stand. Play through 15 levels that start with 51 given digits and strip away clues down to 27 as you climb, with no timer forcing you to wait between rounds — solve a grid and the next one unlocks immediately. Undo mistakes, use a limited hint when you get stuck, and replay any unlocked level for a fresh layout.

How to play Sudoku

1. Tap any empty cell to select it, then tap a number from 1 to 9 on the number pad to fill it in.
2. Every row, every column, and every 3x3 box must contain each digit from 1 to 9 exactly once.
3. A wrong digit is flagged in red right away, so you can back out with Undo or the eraser before it throws off the rest of the grid.
4. Fill every cell correctly to clear the level and unlock the next one.
5. Levels get harder as you go: later grids start with far fewer given digits, so you have to deduce more on your own.

Tips

• Scan for rows, columns, or boxes that are almost full first — they usually leave only one possible digit.
• Use the number pad as a checklist: a digit greys out once it has been placed nine times, so you know it is done everywhere on the board.
• Stuck? Use Undo to back out of a bad guess, or spend a hint to reveal one correct cell.
• On late levels with few givens, work box by box instead of row by row — cross-referencing rows and columns through each 3x3 box narrows the possibilities faster.

FAQ