This puzzle evolved out of wanting to experiment with more than just rectangles/squares to denote regions. The creation of the layout was challenging enough that future experimentation went in different directions.
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.
- Remember: numbers can repeat within a shaded region if that doesn't violate the first rule.