Normal sudoku rules apply. The dots are the centres of rotationally symmetrical “galaxies” of orthogonally connected cells. (ie If you rotate the shape of the galaxy around 180 degrees you must get the same shape.) Each cell in the grid belongs to exactly one of these galaxies. Each row, column, and 3x3 box contains exactly 2 stars, and every galaxy contains exactly 1 star. Stars can't be within a kings move (in chess) from each other. Each galaxy with a small number clue in it sums to the number indicated. Digits can't repeat within a galaxy and “star” cells do not contribute to the totals shown.