Normal sudoku rules apply. In every cage, the digits must sum to 15. The central 3x3 box (in grey) is "semi-magic" ie its rows/columns sum to 15 but its diagonals do not necessarily sum to 15.
Normal sudoku rules apply. In every cage, the digits must sum to 15. The central 3x3 box (in grey) is "semi-magic" ie its rows/columns sum to 15 but its diagonals do not necessarily sum to 15.