Offset Chaos
(Published on 29. January 2025, 00:53 by arbitrary)
- Chaos construction:
Divide the grid into regions, each consisting of nine orthogonally connected cells. Each row, column and region contains the digits 1-9 once each. - Offset X-Sums:
The digit in the first cell next to a black clue indicates the number of cells, including itself, to the first region border seen by the clue.
The value of a black clue is the sum of the first X cells after this region border in the corresponding row/column, where X is the digit in the first cell after the region border.
In every row/column with a black clue, the first X cells after the first region border seen by the clue are in the same region and the X+1th cell, if such a cell exists, is in a different region. - Sandwich Sums:
Red clues further outside the grid give the sum of digits sandwiched between 1 and 9 in that row/column. - Clues represented by the same letter have the same value. Letters do not necessarily have different values. A clue represented by a ? may have any value.
Below is a 6x6 example puzzle. Example link: https://sudokupad.app/ammz4bqyb9.
SudokuPad: https://sudokupad.app/o28qnfl5sc
Solution code: Row 7 with hyphens separating regions e.g. 123-45-6-789
Comments
on 11. February 2025, 21:46 by feverlute
Umm, wow. Before I started I wondered, “how is this enough information to determine both the regions and the digits in them?” And as it slowly resolved, I kept wondering the same thing. How is this happening? It felt like magic. A very satisfying solve.
on 6. February 2025, 15:50 by glum_hippo
Clean, beautiful logic on a very sparse grid. I actually gave it 4 stars but I realize I might be in the minority... With so few clues, it's "easier" in the sense that you don't have to wonder where to look.
on 5. February 2025, 12:40 by GoodMorningCallum
Superb puzzle with some really rewarding and intricate logic. Completely agree that it's all about asking the right questions - and once you do, it's a beautiful solve.
on 1. February 2025, 18:11 by askaksaksask
I solved this the other day and forgot to comment; shame on me for not giving you due cheers earlier! This was a truly brilliant entry in the CC canon. I found the example puzzle to be a useful aid in approaching the main event. Exceptional setting here against what, at first, appears to be an impossibly free rule set. A very narrow solve path, I found, but wholly accessible with some good probing. Truly wonderful. Thank you!
on 31. January 2025, 02:43 by tallcat
Absolutely brilliant. I had several eureka moments throughout the solve. Very consistent path - that forces you to ask the right question. Bravo!
on 30. January 2025, 15:00 by Silverstep
Exquisite creation! So many different types of questions being featured in the break-in sequence. It keeps around the same difficulty going into the irregular section as well.
Agree that it's not too hard and should be on CTC someday
on 30. January 2025, 13:42 by henrypijames
Absolutely miraculous, oh my lord!
And it's not brutally hard (4¼ for me), therefore really a must-do for CtC.
On a cosmetic note, I think it would look better if the sandwich clues are moved to R0 and perhaps given a circle or a shaded background (more colorblind-friendly).
on 29. January 2025, 19:06 by marcmees
Genius CC. Thanks.
on 29. January 2025, 16:19 by kublai
Can I get a rule clarification? Does cell X+1 after the first border in a row/column with a black clue have to be in a different region, or just NOT in the same region? In C5 of the example the 3rd cell after the border is off the grid and therefore NOT in a different region.
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Thanks for pointing out the imprecision in that rule. I've updated it to make clearer that the X-Sum cells can reach the grid edge.
-Arbitrary
on 29. January 2025, 10:36 by Myxo
Brilliant construction. Absolutely baffling how it solves with such minimal clues. Some deductions pushed me to my limits, but the solve path is consistently hard and interesting.
