Play Sudoku online for free
Sudoku is the world's best-known number puzzle: a 9×9 grid, a few given numbers and a single rule. Play it here for free right in your browser – no download and no sign-up.
Every puzzle is freshly generated and has exactly one solution, so you never have to guess: logic alone always gets you there. A game in progress is saved automatically, so you can stop at any time and pick it up later.
Sudoku rules
Fill the empty cells with the numbers 1 to 9 so that every number appears exactly once in each row, each column and each 3×3 box. The given numbers stay fixed. If a number appears twice in a row, column or box, the conflict is highlighted.
Three difficulty levels
- Easy: 40 given numbers – perfect for getting started, 1000 points.
- Medium: 32 givens – for players who know the basic techniques, 2000 points.
- Hard: only 26 givens – you will need notes and patience, 3000 points.
- Each hint costs 100 points.
Controls
- Phone and tablet: tap a cell, then pick the number on the keypad below. The keypad shows how many of each number are still missing.
- Keyboard: arrow keys select a cell, 1–9 enter a number, Del erases, N toggles notes, Ctrl+Z undoes, H gives a hint.
- In notes mode you pencil in small candidates. When you place a number, it is removed automatically from the notes in the same row, column and box.
Tips for beginners
- Scanning: pick one number, say 5, and look at which boxes still lack it. Often only one cell in a box is left where it fits.
- Only choice: look for cells where the row, column and box leave just one possible number – those are safe moves.
- Use notes: from medium upwards it pays to write down all candidates. If two cells in a row share the same two candidates (a "pair"), you can remove those two numbers from the rest of the row.
- Don't guess: every puzzle has a unique logical solution. When you are stuck, look for the number that already appears most often – it has the fewest free places left.
Techniques for hard Sudokus
- Box and line: if a candidate in a box only appears in one row, it has to be in that row. You can remove it from the rest of that row outside the box.
- Hidden pair: if two numbers in a row, column or box only fit into the same two cells, those cells belong to them. Every other note in them goes.
- X-Wing: if a number fits into only the same two columns in two different rows, it sits in those columns in one of the two rows. You can remove it from the rest of both columns.
- On Hard you will often need these techniques. Fill in all the notes first, then work through one number at a time.
Where Sudoku comes from
- The puzzle first appeared in the USA in 1979 as "Number Place", created by the architect Howard Garns.
- The Japanese publisher Nikoli brought it to Japan in 1984 and named it Sudoku, short for "the digits must remain single".
- It became famous worldwide in 2004 and 2005, when the British newspaper The Times and soon many others printed Sudokus every day.
Frequently asked questions
- Is Sudoku on PanicLines free?
- Yes. All puzzles are free to play without an account. There is nothing to buy.
- Can I continue a Sudoku later?
- Yes, your game is saved in the browser after every move. With a free PanicLines account your current puzzle even continues on another device.
- Does every Sudoku have only one solution?
- Yes. Every puzzle is generated so that it has exactly one solution and can be solved without guessing.
- Which level is best for beginners?
- Easy: with 40 given numbers you can usually get through with scanning and the single possible number per cell alone. Notes start to pay off from Medium.
- Does Sudoku work on my phone?
- Yes, the game runs in the browser on smartphones, tablets and PCs and adapts to the screen size. No app needed.
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