Title: Zero Sum

Rating: 3/5

In the first of three consecutive alternate puzzles, here's a sum puzzle with one small tweak. Check out the new first rule.
The official rules:
 The digits 0 through 8 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.