Hyper Sudoku

Hyper Sudoku. Four extra inner-region boxes also must contain digits 1 to 9 with no repeats.

How to play

Fill the 9×9 grid so every row, every column, and every 3×3 box contains the digits 1 to 9 with no repeats — the classic Sudoku rule. Hyper Sudoku adds one twist: Four extra inner-region boxes also must contain digits 1 to 9 with no repeats.

Hyper sudoku, also known as Windoku, keeps the ordinary 9×9 grid but adds four shaded 3×3 windows, each inset one cell diagonally from a corner, and every window must also hold the digits 1 to 9 with no repeats. Because those windows overlap the standard boxes, most of the interesting squares answer to four units at once — row, column, box and window — instead of the usual three. That extra layer is what makes hyper sudoku quick to crack open at the start yet sharper than a plain 9×9 through the middle.

How to solve Hyper Sudoku

Start inside the four windows: any cell that sits in a window is constrained by its row, column, box AND window, so it is the most restricted square on the board and the first place a hidden single tends to surface. Scan each window as a fifth type of unit — a digit with no home in the window's other eight cells gets placed even when the row, column and box alone would leave it ambiguous. The real engine, though, is the overlap: each window straddles four standard boxes, so if a candidate inside a window is trapped in the cells it shares with just one box, you can rub that digit out of the rest of that box — and the reverse holds, a candidate pinned to a box's window cells clears from the rest of the window. Work these locked-candidate swaps in both directions before you turn to the "gap" cells on rows and columns 1, 5 and 9, which lie in no window and only tighten up once the windows are largely filled.

Every Hyper Sudoku puzzle is free to play in your browser — no ads, no sign-up, and it works offline.

Frequently asked questions

What is Hyper Sudoku?

Hyper Sudoku is a 9×9 Sudoku variant — also called Windoku — that adds four extra 3×3 windows to the standard grid. Alongside the usual rows, columns and boxes, each of those four windows must contain the digits 1 to 9 with no repeats, giving every puzzle four bonus regions to solve within.

What are the rules of Hyper Sudoku?

Every row, column and 3×3 box must contain 1 to 9, exactly as in classic Sudoku. On top of that, Hyper Sudoku shades four 3×3 windows sitting at rows 2–4 and 6–8 by columns 2–4 and 6–8 — each inset one cell diagonally from a corner box, with the fifth row and column running between them. Each of those four windows must also contain the digits 1 to 9 exactly once.

Is Hyper Sudoku harder than classic Sudoku?

It is usually a little easier to open and about as demanding to finish. The four windows give you extra units to scan, so early hidden singles come fast and a Hyper grid can ship with fewer starting clues than a classic puzzle of the same rating. But the overlap between windows and boxes creates locked-candidate chains a plain 9×9 never forces, so the mid-game can call for a step classic Sudoku doesn't.