Diagonal Sudoku (X-Sudoku)
Classic 9×9 Sudoku with an extra challenge: both main diagonals must also contain digits 1-9 without repeating.
Rules:
- Fill the grid so each row contains 1-9
- Each column must contain 1-9
- Each 3×3 block must contain 1-9
- NEW: Both main diagonals (highlighted) must contain 1-9
Diagonal cells are highlighted. Fill all cells following the rules.