Irregular Diagonal Sudoku
Combines jigsaw regions with main diagonal constraints
Irregular Diagonal Sudoku is fully playable. Choose a difficulty and start solving.
Jigsaw regions and both main diagonals apply simultaneously, stacking 29 houses onto one 9×9 grid. Cells where a diagonal crosses a snaking region are extraordinarily constrained — and extraordinarily informative. One of the densest, most demanding layouts on the site.
For the complete rules, worked examples and solving techniques, read the full How to Play Irregular Diagonal Sudoku guide.
Like all Sudoku variants, Irregular Diagonal Sudoku builds on the classic 9×9 foundation. Every row, column, and 3×3 box must contain each digit from 1 to 9 exactly once. The variant constraint is added on top of these standard rules, never replacing them.
If you're new to Sudoku, start by learning the basic rules and techniques before attempting variants.
Techniques Useful for This Variant
| Technique | How it applies |
|---|---|
| Pencil Marks / Notes | Essential for tracking candidates alongside the variant constraint |
| Obvious Singles | Cells narrowed to one candidate by the combined constraints |
| Hidden Singles | Digits with only one valid cell in a unit after variant elimination |
| Pairs and Triples | Locked candidates exposed by the additional constraint |