Hyper Sudoku (Windoku)

Hyper sudoku, also called Windoku, is a 9x9 sudoku with four extra 3x3 windows. This free tool lets you play, print and solve hyper sudoku in your web browser; it needs no sign-up and nothing to install. Puzzles are made on your device, and nothing is uploaded.

Every puzzle has exactly one solution, checked by the built-in solver before it is shown. The tool has three tabs. Use Play to solve a puzzle on screen, Print to make worksheets with answers at the end, or Solve to type in your own hyper sudoku and solve it or step through the answer.

How to use the hyper sudoku tool

1. Open the Play tab, which is the default, and press New puzzle to start a puzzle.
2. Tap or click a cell, then tap a digit on the number pad or type it on your keyboard.
3. To write small candidate notes instead of a digit, turn on pencil mode with the Pencil button or the P or Space key.
4. Press Hint when you are stuck. It names the technique for the next step, highlights the cells and explains it in one sentence. If one of your digits is wrong, it tells you to fix that first.
5. Press Check to mark wrong cells in red and see how many cells are left.
6. Press Reveal cell to fill one cell, or Show solution to see the whole answer. Start over clears the puzzle so you can begin again.

Two options help with notes. Turn on “Mark repeated digits in red” to spot clashes, and “Remove pencil marks automatically” so that when you place a digit, its notes disappear from the cells it sees. Undo and redo work with Ctrl/Cmd+Z and Ctrl/Cmd+Y. Arrow keys move the selection, digits enter numbers and Backspace erases.

Your progress is saved in the browser on this device, so a reload continues the same puzzle. Copy link gives a link that opens exactly the same puzzle on another device. The Print tab offers 1, 2, 4 or 6 puzzles per page.

What is hyper sudoku (windoku)?

Hyper sudoku, also called Windoku, is a sudoku variant on a 9x9 grid. It keeps the normal sudoku rules and adds four extra 3x3 windows, shaded on the grid and placed one cell in from the edges.

The windows cover rows 2 to 4 and rows 6 to 8, crossed with columns 2 to 4 and columns 6 to 8. Each window must contain the digits 1 to 9 once, just like a row, column or box.

How to play hyper sudoku?

Fill every empty cell with a digit from 1 to 9. Each row, column, 3x3 box and window must contain each digit exactly once. That makes 31 groups that must hold 1 to 9, compared with 27 in a normal sudoku, so hyper puzzles can be solved with fewer starting clues.

Two solving techniques help. A Hidden Single is a digit that fits in only one cell of a row, column, box or window, so it must go there. A Naked Pair is two cells in the same group that can hold only the same two digits. Those two digits can be removed from the other cells in that group. Working with pencil notes makes these patterns easier to spot. The windows overlap the corner boxes and the middle row and column of boxes, so a digit placed in a window also limits two or more boxes at once; start where a window and a box share four cells.

Can I print hyper sudoku?

Yes. The Print tab makes hyper sudoku puzzles ready to print, with 1, 2, 4 or 6 puzzles on a page. The answers are printed at the end, so you can check your work after you finish.

Is there a hyper sudoku solver?

Yes. The Solve tab lets you type in a hyper sudoku and either solve it or step through the solution one move at a time. The solver applies the window rule, so the four windows are checked along with the rows, columns and boxes. Stepping through is useful when you want to see why each digit goes where it does.

Frequently asked questions

Is hypersudoku the same as hyper sudoku?

Yes. Hypersudoku is just the one-word spelling of hyper sudoku, and both names refer to the same puzzle with four extra windows.

Can I use the tool for windoku puzzles?

Yes. Windoku is another name for hyper sudoku, so the Play, Print and Solve tabs all work with windoku puzzles.

Is hyper sudoku harder than normal sudoku?

Not necessarily. The four windows add rules, which also gives you more information. This page rates puzzles easy, medium or hard by the techniques they need, the same way as classic sudoku.

Is the tool free to use?

Yes. It is free, needs no sign-up and has nothing to install. It runs in your web browser.

Can I continue a puzzle on another device?

Yes. Progress is saved in your browser on the device you are using, so a reload continues the same puzzle. Press Copy link to get a link that opens exactly the same puzzle on another device.

What happens if I put in a wrong digit?

Press Check and wrong cells are marked in red, and the timer and remaining-cell count help you track progress. If you ask Hint for help while a digit is wrong, it tells you to fix that digit first.

Related tools

• Diagonal sudoku: Use it when you want a sudoku where both main diagonals must also hold 1 to 9.
• Jigsaw sudoku: Use it when you want irregular regions in place of the normal 3x3 boxes.
• Sudoku solver: Use it to solve a standard sudoku you have typed in.
• Sudoku generator: Use it to create new standard sudoku puzzles.
• Printable sudoku: Use it when you want standard sudoku worksheets to print.
• Killer sudoku: Use it when you want a sudoku that uses cage totals as clues.
• How to play sudoku: Use it when you want a beginner’s guide to the standard sudoku rules and techniques.