How to Play Sudoku
Sudoku is a logic-based number puzzle. The goal is to fill a 9x9 grid so that every row, column, and 3x3 box contains the digits 1 through 9 exactly once. No math is required — just logical deduction.
1. Read the grid
Some cells are pre-filled with given numbers. These cannot be changed. Your job is to fill in the remaining empty cells.
2. Place numbers
Tap an empty cell to select it, then tap a number from the keypad to place it. Use Notes mode to pencil in candidates you are considering.
3. Solve the puzzle
Keep filling cells until every row, column, and 3x3 box has all nine digits. You have 3 hints per game, and conflicts are highlighted in red so you can spot and fix mistakes.
Tips for Sudoku
- Start with scanning. Look for rows, columns, or boxes that are nearly complete and fill in the missing digits.
- Use pencil marks. Toggle Notes mode to jot down candidate digits in cells where you are unsure. This helps you eliminate possibilities.
- Look for naked singles. If a cell has only one possible candidate, that must be the answer.
- Check cross-hatching. If a digit can only go in one place within a row, column, or box, fill it in even if other cells in that area are empty.
- Save hints for later. Use your 3 hints on the hardest cells rather than early obvious ones.
Frequently Asked Questions
What are the rules of Sudoku?
Fill every row, column, and 3x3 box with the digits 1 through 9. Each digit may only appear once per row, column, and box. The puzzle starts with some given digits that serve as clues.
How many difficulty levels are there?
Four: Easy, Medium, Hard, and Expert. Harder puzzles have fewer starting numbers and require more advanced solving techniques.
Is there a new puzzle every day?
Yes! A new daily puzzle is generated for each difficulty level every day. You can also play unlimited random puzzles in Unlimited mode.
What happens when I make a mistake?
If you place a digit that duplicates another in the same row, column, or 3x3 box, all conflicting cells are highlighted in red. The digit stays in the cell — there is no mistake limit. Fix the conflict whenever you're ready, or use undo or hints to help.
About Sudoku
Sudoku is one of the world's most popular logic puzzles. It was popularized in 1986 by the Japanese puzzle publisher Nikoli and became a global phenomenon in 2005 when newspapers worldwide began publishing it daily.
Our version features four difficulty levels, pencil marks, hints, undo support, and automatic progress saving for daily puzzles. Each daily puzzle is deterministically generated, so every player gets the same puzzle on the same day.