About Sudoku
Sudoku is a logic puzzle played on a 9×9 grid divided into nine 3×3 boxes. Every puzzle here has exactly one solution and can be solved by reasoning alone — no guessing needed. Pick a difficulty or take on today's daily challenge and compare your time with players around the world.
How to play
Fill each empty cell with a digit from 1 to 9. Each row, each column and each 3×3 box must contain every digit exactly once. Use notes to pencil in candidates.
Tips and strategies
- Start with rows, columns and boxes that are nearly full — they leave the fewest candidates.
- Use notes to pencil in candidates, then look for cells with only one possible digit.
- If a digit can only go in one row inside a box, remove it from the rest of that row.
Sudoku strategy guide
Scan before you write. For each digit from 1 to 9, look at every box and ask where that digit can still go. When the other boxes in a band already hold the digit in two rows, the third copy has only one row left — these hidden singles solve most of an easy grid.
When scanning runs dry, switch to notes. Pencil the possible digits into the empty cells of a row, column or box, then look for a cell with a single candidate (a naked single) or a digit that fits only one cell of a unit (a hidden single).
On hard and expert grids, look for pairs: if two cells in a unit can only hold the same two digits, remove those digits from every other cell of that unit. Pointing pairs work the same way — if a digit in a box is confined to one row, strike it from the rest of that row.
Frequently asked questions
Does every Sudoku here have exactly one solution?
Yes. Every puzzle is checked by a solver before you see it, so it has exactly one solution and can be finished by logic alone, without guessing.
What is the difference between easy and expert Sudoku?
The number of starting clues: about 40 on easy, 33 on medium, 28 on hard and 24 on expert. Fewer clues mean longer chains of reasoning before the next digit is certain.
Can I use hints?
Yes. Press Hint (H) to fill in one correct cell. Each hint uses one of your hints (3 free every day) and adds 30 seconds to your time; the game still counts on the leaderboards.
Is Sudoku free to play?
Yes. Every game on Puzzimo is completely free and runs in your browser on desktop, tablet and phone — no download or installation.
Do I need an account?
No. You can play instantly as a guest and still appear on the leaderboards. Sign in with Google, Discord or LINE to keep your scores on every device.
How does the daily Sudoku challenge work?
Every day at 00:00 UTC everyone gets the same new puzzle. Only your first finish of the day counts on the leaderboard.
How are leaderboard results verified?
Our servers replay every move of your game and measure the time themselves, so leaderboard results can't be faked.