Normal sudoku rules apply. Digits along a blue line sum to the same value in each 3x3 box the line passes through. Different lines may have different sums. eg r1c2 + r2c2 + r3c2 = r4c3 + r5c3 + r6c3 = r7c2 + r8c2 + r9c2. Cells separated by a black dot contain digits in a 1:2 ratio (ie one digit must be double the other). Cells separated by a white dot must contain consecutive digits. Not all dots are given.