Sudoku Variant 2: Diagonal Sudoku

Welcome to Diagonal Sudoku (Sudoku X)! In addition to rows, columns, and 3×3 boxes, both main diagonals must contain digits 1–9 with no repeats. Cells on diagonals are highlighted.

📐 Diagonal Sudoku — Both Diagonals 1–9

💡 Highlighted cells are on diagonals. Both main diagonals must contain all digits 1–9.

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# What Is Diagonal Sudoku?

Diagonal Sudoku (Sudoku X) adds one rule: both main diagonals must contain 1–9 with no repeats. Diagonal cells (highlighted pink) are constrained by row + column + box + diagonal — the center cell sits on BOTH diagonals!

🧠 Pro Tip: Start with the center cell (r5c5) — it's on both diagonals and is the most constrained cell on the board.

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