Modular Islands
(Published on 23. March 2026, 21:54 by Killer Joe)
Hello.
Normal Sudoku rules apply.
Digits are grouped into modular sets:
mod 1 → {1, 4, 7}
mod 2 → {2, 5, 8}
mod 0 → {3, 6, 9}
A digit placed in a circle indicates the size of the orthogonally connected group of cells that all contain digits from the same modular set as that digit.
No group contains more than one circled cell.
Not all groups contain a circle.
Digits separated by a white dot must be consecutive.
Have fun.
Solution code: Row 9, first 6 digits.
Comments
on 3. April 2026, 11:48 by bboom
Fun coloring puzzle, and more straightforward than it seemed at first glance
on 3. April 2026, 01:16 by Killer Joe
Changed 'regions' to 'groups' for clarity.
on 28. March 2026, 13:26 by anothermember
The constraint is so strong it practically solves itself.
on 28. March 2026, 10:34 by botteur
Surprisingly easier than it looked. Thanks!
on 24. March 2026, 22:00 by faltenin
That was fun! Looked confusing at first then the constraints started to become clear. Good job, thanks.
on 24. March 2026, 21:25 by dzamie
I've been playing a lot of The Artisan of Glimmith recently, and this puzzle reminded me a lot of it. I found both the Pen and Coloring tools useful as I made my way across the grid.
on 24. March 2026, 10:05 by Exigus
Very interesting ruleset. Thanks!
