Sudoku X — Diagonal Sudoku Variant

Sudoku X follows the usual rules — every row, column, and 3×3 box holds the digits 1 to 9 exactly once — and adds one more: both main diagonals must also contain 1 to 9 with no repeats. The extra constraint means the diagonals give away placements an ordinary grid would not, so the same clue count solves differently.

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