🪟 How to play Windoku (Hyper Sudoku)
By Miguel Arechaga
Windoku, also known as Hyper Sudoku or NRC Sudoku, is a variant of classic sudoku that adds four extra regions to the board. Its name comes from the four shaded boxes looking like the "windows" of a building. It's a very elegant variant: few new rules, but a lot of extra logic. Here are the rules and a few tips.
What is Windoku?
It's a standard 9x9 sudoku with four extra 3x3 boxes added, positioned interior to the grid and separated from each other (shaded on the board). Each of these four windows must also contain the numbers 1 to 9 without repeats, in addition to the usual rules.
Rules and how to play step by step
- The sudoku rules apply: 1 to 9 without repeats in each row, column and 3x3 box.
- In addition, each of the four shaded boxes must contain 1 to 9 without repeats.
- You start with some clue cells and fill in the rest with logic. Every puzzle has a unique solution.
Tips to solve Windoku
- Start with the windows: shaded cells carry one extra constraint (row, column, box and window), so they usually have fewer candidates and get solved first.
- Cross information between windows and boxes: many cells belong to both a regular box and a window; use both to eliminate candidates.
- Apply the last-number rule to windows too: if a window is missing only one number, you already have it.
- Combine everything with the classic elimination techniques of sudoku.
How it differs from regular sudoku
Compared to classic sudoku, Windoku adds four more regions, giving you more starting clues but requiring you to track more constraints at once. If you enjoy variants with extra regions, you'll also enjoy Sudoku X (Diagonal Sudoku) and Jigsaw Sudoku.
