Irregular Diagonal Sudoku
Combines jigsaw regions with main diagonal constraints
Easy
Irregular Diagonal Sudoku Easy
Medium
Irregular Diagonal Sudoku Medium
Hard
Irregular Diagonal Sudoku Hard
Expert
Irregular Diagonal Sudoku Expert
What is Irregular Diagonal Sudoku?
Irregular Diagonal Sudoku combines two variant types: the irregular jigsaw regions of Jigsaw Sudoku and the diagonal constraints of Diagonal Sudoku. Both main diagonals and all irregular regions must contain 1–9. The combination creates highly constrained puzzles with unique solving logic.
At a Glance
| Constraint type | Combined: Irregular + Diagonal |
| Typical givens | 22–30 |
| Difficulty rating | ★★★★☆ 4/5 |
| Avg. solve time — Easy | 8 min |
| Avg. solve time — Medium | 18 min |
| Avg. solve time — Hard | 35 min |
| Avg. solve time — Expert | 65 min |
How to Solve Irregular Diagonal Sudoku
| Technique | What it does | Level |
|---|---|---|
| Map All 29 Units First | You have 9 rows + 9 columns + 9 irregular regions + 2 diagonals = 29 constraint units. Identify all irregular regions and both diagonals before starting. | Beginner |
| Diagonal–Region Intersection | Cells on a diagonal that also sit in the same irregular region create a powerful two-unit intersection — use both constraints simultaneously. | Intermediate |
| Diagonal Pointing Pairs | If a digit on a diagonal is confined to one irregular region, eliminate it from all other cells of that region. | Intermediate |
| Region Coloring for Diagonals | Trace which irregular regions each diagonal passes through. Regions with many diagonal cells are the most constrained. | Advanced |
| Chain Deduction Across Units | With 29 units, a forced digit in one unit often cascades through 3–4 other units. Track chains carefully to avoid errors. | Advanced |
Average Solve Times
Easy
8 min
Medium
18 min
Hard
35 min
Expert
65 min
Frequently Asked Questions
Which diagonals are constrained?
Both main diagonals: top-left to bottom-right and top-right to bottom-left.
Are the regions always the same shape?
No — irregular regions are randomly generated per puzzle with different boundaries each time.
How many constraint units does the centre cell belong to?
The centre cell (row 5, col 5) is on both diagonals, plus its row, column, and irregular region — 5 units total.