Windoku Sudoku

Rules

Windoku adds four 3×3 windows that behave like extra boxes: each must contain the digits 1–9 exactly once. They overlap the normal boxes, so a digit can be excluded from a cell by eight different units.

• The four shaded 3×3 windows each contain 1–9 exactly once.
• Normal rows, columns and boxes still apply.
• Every window overlaps four ordinary boxes, so clues multiply.
• Cells in the centre are constrained by a row, a column, a box and usually two windows.

Good to know

Ordinary sudoku rules still apply underneath the variant: every row, column and 3×3 box holds 1–9 exactly once. The extra rule sits on top and is usually what breaks the puzzle open.

More sudoku

All sudoku variants ↗

Or read how to play Sudoku ↗.