Place the digits 0 to 8 once each in every row, column and 3x3 box. One cell in every row, column and box is a “doubler”. This cell counts as double its value for the rules below. Each of the digits 0 to 8 appears exactly once in a doubler cell. Values on an X sum to 10. Values on a V sum to 5. Digits in a cage may not repeat. Values in a cage sum to the total in the top-left most corner of the cage. The grid is partially covered in fog. Placing correct digits will clear the fog from surrounding cells. Guessing is not necessary.