Normal sudoku rules apply. Placing a correct digit may clear fog somewhere in the grid – no guessing is required. The digits along a purple line contain consecutive digits in any order without repeats. Each purple line is in the shape of a square. Similarly, the digits along a grey line contain consecutive digits in any order without repeats. Each grey line is also in the shape of a square. Cells separated by an X sum to 10 and, in cells separated by a black dot, one digit is double the other.