Play Sudoku Online for Free
Sudoku is a classic logic puzzle played on a 9×9 grid. Your goal is to fill every empty square with a digit from 1 to 9 so that no digit repeats in any row, column or 3×3 box. This version on Aitchy.Games runs directly in your browser and includes five difficulty levels, pencil notes, hints, undo and redo, a timer, autosave and a new daily puzzle.
How to Play Sudoku
- Select any empty square in the 9×9 grid.
- Choose a number from 1 to 9 using the number pad or your keyboard.
- Make sure the number does not duplicate another number in the same row, column or 3×3 box.
- Use Notes to record possible candidates when more than one value could fit.
- Complete all 81 cells correctly to solve the puzzle.
You do not need arithmetic to solve Sudoku. The numbers work as nine different symbols; the challenge is deciding where each symbol can legally appear.
Sudoku Difficulty Levels
The number of starting clues is one factor in puzzle difficulty, but it is not the only one. The sequence of logical deductions required to reach the solution also matters, so two puzzles with a similar number of clues can feel different to solve.
| Level | Best for | What to expect |
|---|---|---|
| Easy | Beginners | More starting clues and frequent direct placements. |
| Medium | Regular players | More scanning and candidate elimination. |
| Hard | Experienced players | Fewer obvious placements and longer deduction chains. |
| Expert | Advanced solvers | Sparser grids where careful notes become more useful. |
| Master | Challenge seekers | The fewest clues in this game and the most demanding search for deductions. |
Useful Sudoku Strategies
Scan rows, columns and boxes
Before adding notes everywhere, look for a row, column or 3×3 box that is nearly complete. If only one digit is missing, that value is forced.
Use candidate notes
For harder puzzles, record the digits that could still fit in an empty cell. As other numbers are placed, eliminate candidates until a cell or a unit has only one possible choice.
Look for hidden singles
A cell can have several candidates but still be the only place for a particular digit within its row, column or box. That digit must go there.
Recheck the whole grid after a placement
One correct number can unlock several other cells. After every useful placement, scan its row, column and box again before moving on.
Daily Sudoku
Select Daily above to play a puzzle tied to the current date and chosen difficulty. The same device can keep your progress if you leave the page and return later. Random mode is available whenever you want another puzzle immediately.
Sudoku FAQ
How do you play Sudoku?
Fill every empty cell so each row, each column and each 3×3 box contains the digits 1 through 9 exactly once.
Is this Sudoku game free?
Yes. You can play it for free in your web browser without installing an app or downloading a game file.
Can I use notes?
Yes. Turn on Notes and select digits to add or remove pencil marks. Auto Candidates can also populate all candidates that are currently legal according to the numbers on the board.
Does my Sudoku progress save automatically?
Yes. The current puzzle and local statistics are stored in your browser. Clearing browser storage or using a different device will reset that local data.
What happens if I enter a wrong number?
An incorrect entry is shown in red and the mistake counter increases. You can erase it, undo the move, or use Check Progress to locate incorrect entries.