Killer Kropki
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Apply classic sudoku rules.
A white dot between two dotted outlined regions indicates that the sums within those regions have a difference of one. A black dot between two such regions indicates that one of the sums is twice the other sum. When there is no dot between two regions, they cannot have sums that differ by one or are double. Digits may not be repeated in regions.
Sudokupad (no answer check)
Sudokupad (with answer check)
or
Penpa+.
Solution code: Row 9
on 23. February 2026, 19:40 by dzamie
Definitely easier than the "full version" the advent puzzle was based on, but definitely much harder than the advent puzzles.
Still, a lot of fun! I really enjoy this variant.
on 22. February 2026, 14:33 by Franjo
Thank you very much for creating and sharing another lovely puzzle. The negative constraint did a great job.
on 18. February 2026, 12:18 by Snookerfan
Beautiful, thanks!
on 18. February 2026, 11:55 by marcmees
Great logical flow, interesting till the very end. Thanks
on 18. February 2026, 08:54 by Piatato
Lovely!