Normal sudoku rules apply. Additionally, shade some cells such that the clues outside the grid indicate the sums of the digits in contiguous blocks of shaded cells in the respective row or column. Blocks have to be separated by at least one unshaded cell. So a 6 clue in a row could mean a single-cell 6 is shaded, or a 2/4 pair is shaded, or a 1/2/3 triple is shaded. There must be a 3x3 magic square completely in the shaded region of the correct solution.