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Jigsaw Sudoku

Sudoku with non-rectangular regions. same digit constraint, weirder shapes.

Jigsaw·00:00

What jigsaw sudoku feels like.

Jigsaw sudoku. also called squiggly or geometric sudoku. keeps the row and column rules of classic sudoku but replaces the nine 3×3 boxes with nine irregular regions of nine cells each. The same digit constraint applies, but the geometry forces you to think spatially.

Rules

  1. Each row contains digits 1-9 exactly once.
  2. Each column contains digits 1-9 exactly once.
  3. Each irregular region of nine cells contains digits 1-9 exactly once.
Key rule
Irregular regions replace 3×3 boxes
Difficulty range
Medium to evil
Tips
  • Long, snake-like regions create unusual elimination paths. scan them carefully.
  • Pointing pairs and box-line reduction take on new forms; the 'box' is now whatever shape the region happens to be.
  • Pencil marks are essential.

Jigsaw Sudoku FAQ

What's the difference between jigsaw and classic sudoku?
Only the box shape. In classic sudoku, the nine boxes are 3×3 squares. In jigsaw, they're irregular polyominoes of nine cells each.
Are jigsaw regions always nine cells?
Yes. Every region in a 9×9 jigsaw sudoku has exactly nine cells; otherwise the digit constraint can't be satisfied.
Is jigsaw sudoku harder than classic?
Generally yes, because spatial intuition about boxes has to be rebuilt from the region shapes.
Can I use the same techniques as classic sudoku?
Most of them, yes. they just look different. X-wing and swordfish work identically; box-line reduction generalises to region-line reduction.
Are jigsaw puzzles unique?
Yes. Uniqueness is verified during generation.