Play X-Sudoku (Diagonal Sudoku) Online Free

Play X-Sudoku online for free. Standard rules plus both main diagonals must also contain 1-9 with no repeats.

▶ Play X-Sudoku (Diagonal Sudoku) — Free
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How to Play X-Sudoku (Diagonal Sudoku)

  1. Standard Sudoku rules: rows, columns, and 3×3 boxes contain 1-9.
  2. PLUS: both main diagonals must also contain digits 1-9 with no repeats.
  3. The top-left to bottom-right diagonal is one extra constraint.
  4. The top-right to bottom-left diagonal is another.
💡 Pro Tip
The center cell (r5,c5) belongs to both diagonals, its row, column, and box — 5 constraints instead of the usual 3.

Frequently Asked Questions

How many extra constraints does X-Sudoku add?

Two — one for each main diagonal. Cells on the diagonals have 4 constraints instead of 3, making them more restricted.

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▶ Play X-Sudoku (Diagonal Sudoku)