Chiaroscuro-doku
(Published on 8. March 2025, 02:03 by yttrio)
Rules:
Normal Sudoku rules apply.
Chiaroscuro: Shade some cells so that all groups of orthogonally connected shaded cells have an even number of cells and all groups of orthogonally connected unshaded cells have an odd number of cells. Two groups cannot have the same shape and size, counting rotations and reflections as the same.
Digits cannot repeat within a Chiaroscuro group.
A digit in a circled cell is equal to the size of the Chiaroscuro group which contains that cell.
If a cell has a given number in the upper left corner, then the digits in the Chiaroscuro group which contains that cell must sum to that number.
6x6 Example:
The image below shows a sample 6x6 puzzle and solution with the same rule set.
Play the example 6x6 in SudokuPad.
Solution code: Digits in shaded cells in row 7 (left to right), followed by digits in shaded cells in row 9 (left to right)
Comments
on 15. July 2025, 06:37 by psams
I enjoyed this construction, and the need to consider total digits in more than one group of cells as a cluster. It would be interesting to further explore the shape repeating rule, and cells whose shading remains ambiguous a long time, and possibly more than two shading colors.
on 20. June 2025, 10:35 by etoler
Another day, another fantastic yttrio puzzle. It took me a minute to get my head around all the implications of the rules, but once you get your bearings, it's SO pretty the way it flows.
on 3. May 2025, 08:25 by sfushidahardy
Really lovely puzzle! Sadly due to my inexperience with sudoku, the "post-chiaroscuro" portion of the solve took about three times longer than everything that came before it. I could tell that the sudoku wasn't supposed to be difficult though :p
on 26. March 2025, 22:27 by Agent
Beautiful puzzle, very smooth!
on 22. March 2025, 18:00 by Christounet
Incredible. Thanks:)
on 12. March 2025, 08:01 by waffles_the_dog
This was a really nice puzzle. I haven't tried this kind of constraint before and it resulted in some really interesting interactions.
Thank you so much for setting it, I still have no idea how you construct such wonders :D
on 11. March 2025, 20:08 by puzzlepandit
That's a very brilliantly set puzzle. very bice yttrio. Solving small one first helps a lot.
on 10. March 2025, 23:04 by askaksaksask
Great ruleset. I thought most of the logic here was very fresh, albeit wholly accessible. Really well constructed to have this kind of flow with some fun hurdles. Thank you for this great puzzle!!
on 10. March 2025, 00:21 by skuntsel
Brilliant and innovative variant as ever, yttrio! On an easier side of 3-4 star puzzles, but that’s maybe because I’ve solved a few of those harder recently. But nonetheless never boring and always keeping you in shape for further steps. I liked how and when different shapes came into the spotlight to disambiguate everything especially in the end. Thank you for this excellent puzzle, I liked every minute solving it.
on 9. March 2025, 12:09 by Chaka
I know you are capable of setting brillant sudokus, yttrio, but the logic in here is extraordinary! Thank you for sharing this!
on 9. March 2025, 10:19 by sorryimLate
So so nice once again. Thanks!
PS I probably had a different solve path than intended because I never used the 32-clue.
on 8. March 2025, 20:35 by RedBarchetta
100% amazing! I opened this up and thought no way - too tough - new rules to me. But I gave it a go. And once I understood and then kept applying the rules, it was just so satisfying! I forgot the rules near the end and was sure I broke it. Nope - satisfying to the end, thanks!
on 8. March 2025, 19:26 by Godrick
This was very nice. Thank you so much. I think it is on the "easier" side of a 4-star puzzle (which is very nice too). Very well done!
on 8. March 2025, 15:45 by Al Fresco
Wonderful puzzle. Thank you :)
I predict this will put a big smile on Simon’s face, assuming he tries it.
on 8. March 2025, 12:38 by Franjo
Checkered Sudoku - I love this! Thank you very much for creating and sharing this extraordinary puzzle.
on 8. March 2025, 10:52 by Snookerfan
Brilliant puzzle and ruleset! Thank you
on 8. March 2025, 02:22 by Calvinball
This is the sudoku hybrid I didn't know I was waiting for. I laughed, I cried, it had it all.
