Logic Masters Deutschland e.V.

1. Normal sudoku rules apply.
2. Primes can't project on the same digit through rotational symmetry (±90 or 180 degrees).
3. One of the prime digits is special, must appear in the shaded cell, and can't ever repeat diagonally.
4. In boxes where the special digit appears on the box diagonals, digits in each box row are sequential modulo 9, e.g., [1 2 3] or [8 9 1].

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