How to Play Jigsaw Sudoku

Irregular Sudoku (also called Jigsaw Sudoku) replaces the standard nine 3×3 boxes with nine irregularly-shaped regions of exactly nine cells each. Every row, column, and irregular region must still contain the digits 1–9 exactly once. The regions are colour-coded or outlined with thick borders.

Each region is shaded in a distinct colour or enclosed by thicker lines. Count the cells in each region to confirm it has exactly nine. The regions are always connected — no region is split across the grid — but they can have any shape as long as they tile the full 9×9 grid.

The logic is identical — you use the same techniques (naked pairs, hidden singles, pointing pairs, etc.) — but the non-rectangular region shapes create different constraint interactions. A region that snakes diagonally creates eliminations in many different rows and columns simultaneously, which can feel unintuitive at first.

At easy difficulty, Irregular Sudoku can be harder because the region shapes are less predictable than 3×3 boxes. At higher difficulties, experienced Sudoku players often find it comparably challenging — the same techniques apply, just with different geometry.

Trace each region carefully before starting — understand its shape and which rows and columns it spans. Regions that span many different rows and columns create more powerful constraints. Focus on regions with the most given digits first, then use pointing pairs to transfer information between regions and lines.

Easy puzzles take 8–20 minutes. Medium puzzles run 20–40 minutes. Hard and expert puzzles can take 45–90 minutes. Familiarity with jigsaw region shapes speeds up solving considerably after a few practice puzzles.