The official rules:
- The digits 1 through 9 appear in each row and each column exactly once.
- Digits in each shaded region must add to the indicated sum.
- Squares with multiple colors contain a number that’s used in the sum for adjacent regions of each of those colors.
- Cells at the following positions belong to the regions that go horizontally and vertically through that cell: (2,2), (2,8), (8,2), (8,8). The (light purple) color of these cells is the RGB-average of the colors from the horizontal and vertical regions that intersect there.
- Remember: numbers can repeat within a shaded region if that doesn't violate the first rule.