All Sudoku Variants
9×9 · Constraint

Girandola Sudoku

A ninth region of nine marked cells in a pinwheel — the four corners, the centre, and four cells set out from the centre along each side — must also contain the digits 1–9.

3 7 5 2 9

An example Girandola puzzle: the nine shaded pinwheel cells form an extra region that must hold 1–9.

Girandola Sudoku adds a ninth region shaped like a pinwheel — a girandola is a revolving firework. Nine marked cells (the four corners, the centre, and four cells set out toward each side) must also contain the digits 1–9 exactly once, on top of the usual rows, columns and boxes. It is a fixed-shape cousin of Asterisk and Center Dot Sudoku.

The rule: the pinwheel is a tenth unit

Treat the nine shaded girandola cells as an extra region: together they must hold 1–9 with no repeats. They sit one per box, so the region ties all nine boxes together.

The nine shaded girandola cells form an extra region that must hold 1–9.

How to use the pinwheel

Because the girandola cells sit one per box, a digit placed in one of them is barred from the other eight — the region reaches across the whole grid. Scan it like any unit: if eight of its cells are known, the ninth is forced, and a digit crowded across several boxes is quickly pinned to its one remaining girandola cell.

Solving strategy

  • Treat the pinwheel as a region. Hunt hidden singles within it exactly as you would in a box.
  • Use its long reach. The nine cells span all nine boxes, linking corners and centre that the ordinary rules keep apart.
  • Finish near-full pinwheels. Eight known girandola cells give the ninth for free.
  • Feed the grid. Each girandola digit placed behaves like a given for its row, column and box.

Common mistakes

  • Forgetting the pinwheel is a full unit. All nine cells need 1–9, not merely "no repeats with their boxes".
  • Misplacing the cells. The girandola is a fixed shape — check exactly which cells are marked before you rely on it.
  • Scanning it in isolation. Its power is where it overlaps the boxes and lines.
  • Dropping the ordinary rules. Rows, columns and boxes still apply on top of the pinwheel.

Can I play it here?

Not yet — Girandola Sudoku isn't one of the puzzle types SudokuStreak generates for now. But you can learn its rules above, and there's plenty here to sink your teeth into meanwhile: