Zone Coverage

I’ve solved more than 1200 computer-generated Killer Sudoku puzzles on a daily site, but there’s a definite sameness to them. Just having some cages without totals makes these puzzles different, and I enjoy each one as much as a dozen on the daily site.

I would say that, though, wouldn’t I?

Rules:
Normal Sudoku rules apply.
Digits within cages do not repeat, and sum to the total in the top-left corner of the cage, if given.

Estimated difficulty: 1.5 out of 5