Windoku.
Learn the rules, see the possibilities.
Windoku adds shaded window regions to a Classic Sudoku board. On the standard 9×9 puzzle, four extra 3×3 windows each need the digits 1–9 exactly once. These regions are offset from the normal boxes, so a single cell can connect several different sets of constraints.
How to play Windoku Sudoku
Three ideas. Illustrated on the board. Take them one move at a time.
Find the four extra windows
The shaded windows are extra groups, not decorations. On a 9×9 board they occupy rows 2–4 and 6–8, paired with columns 2–4 and 6–8. Each window must contain a complete set of 1–9. Keep these offset regions separate from the nine regular boxes.
A normal box follows thick grid lines; a window follows its highlighted area.
Solve one window at a time
Choose a window with several known values. Work out which digits are missing, then check the possible positions inside that window. Each candidate must also fit the cell’s row, column, and normal box. A digit can appear once in each of the four different windows, just as it can appear once in different boxes.
Do not treat all highlighted cells as one giant group. Each window has its own no-repeat rule.
Use the overlap to eliminate candidates
A window cell belongs to a row, a column, a standard box, and an extra window. Check all four before placing a digit. If a digit has only one possible position in a window, that cell is forced even when its row or box still has several empty spaces.
Switch between regular boxes and windows when one type of group stops giving new information.
Sudoku strategies that work in every variant
Every Sudoku is solved with the same three habits. They need no arithmetic and no guessing — just a careful look at what each cell can still be.
Scan rows, columns, and boxes
Pick a number and sweep the grid. Where a number already appears, it cannot go again in that row, column, or box. Three placed copies often leave only one open cell for the fourth.
Hunt for singles
Look for a cell with just one possible symbol left. A row or box that is almost complete is the fastest place to find one, and each single you place narrows the next cell.
Write candidates, then eliminate
When two or three cells stay open, switch on Notes and pencil in the possibilities. Cross out candidates as peers fill in. If a digit fits only one cell inside a group, that cell must hold it.
A few Windoku Sudoku facts
Extra windows on 9×9
Each window adds one all-different group.
Window cells on 9×9
Four separate windows contain nine cells each.
Total groups on 9×9
The usual 27 Sudoku groups plus four windows.
These examples and figures describe a standard 9×9 board unless otherwise stated.
Make yourself at home on the board.
Choose a cell, enter a symbol, and keep going. Use Notes for possibilities, Undo to revisit a move, and Hint when you need a nudge. Change the visual theme without changing your game.
- ↑↓←→
- Move between cells
- 1–9
- Enter a number; use the keypad for larger symbol sets
- Del
- Erase your entry
- Ctrl / ⌘Z
- Undo the last move
Windoku Sudoku, explained.
A few things you might be wondering.
Are the shaded Windoku windows the same as regular boxes?
No. Regular boxes follow the thicker grid lines. Windoku windows are additional offset regions that cross some of those box boundaries.
Can the same number appear in two different windows?
Yes, provided its placements obey all the other Sudoku constraints. Each individual window must contain 1–9 once; the four windows are separate groups.
How does the 16×16 Windoku board differ?
Sudokuzz uses 4×4 standard boxes and nine highlighted 4×4 windows on its 16×16 Windoku board. Every row, column, standard box, and window needs all sixteen symbols once.