9×9 · Medium to expert
Hyper Sudoku
Classic sudoku with four extra 3×3 regions to satisfy.
About hyper
What hyper sudoku feels like.
Hyper sudoku. also called windoku. adds four extra 3×3 regions inside the grid, offset from the standard boxes. Each of those four extra regions must also contain digits 1 through 9 exactly once. The added constraints tighten the puzzle considerably.
Rules
- Standard 9×9 sudoku rules apply.
- Four extra 3×3 regions at rows 2–4 and 6–8, columns 2–4 and 6–8, each contain digits 1–9 exactly once.
- Key rule
- Four extra 3×3 regions also contain 1–9
- Difficulty range
- Medium to expert
- Tips
- The cells inside the four extra regions are heavily constrained. start there.
- A digit placed in the centre cell of the grid (5,5) lies in two regions at once if your variant uses the central hyper-region.
- Pencil marks are nearly mandatory for hyper sudoku above easy.