Normal sudoku rules apply. Identical digits may not be a knight's move apart. Each row, column, and box contains exactly two stars. Stars may not touch orthogonally or diagonally. Stars also contain digits and behave as normal Sudoku cells. Any digit orthogonally adjacent to a star must differ from the star's digit by at least 3. A clue outside the grid gives the sum of star digits along the indicated diagonal (only star cells count).