Liar X-Sums Chaos Construction
(Published on 23. January 2026, 08:33 by Christounet)
[NOTE : this is a re-upload of a puzzle I published before, but with a wrong clue I copied from an earlier draft (which is ironical for a "liar" puzzle). Sorry to anyone who tried it before! This one should be good.]
A couple days ago, I published with rdrd a first challenging puzzle with liar X-Sums. This one should be on the easier side. It is my first 9x9 chaos construction. I tried my best to keep a good balance between region building and an approachable irregular sudoku resolution. Difficulty should be around 4, or maybe less if you are familiar with chaos construction. Do try the example first, it should be a fun easy intro to the concept. Have fun solving!
Thanks to rdrd for testing!
The puzzle :
Rules :
- Normal sudoku rules apply
- Chaos construction : Place the digits 1 to 9 once each in every row, column and region. Regions are orthogonally connected and must be located by the solver.
- X-Sums : Clues outside the grid represent the total of the first X digits in that direction, with X being the digit in the first seen cell. The clue also indicates that the first X cells in the row/column from that direction are in the same region, and the next cell (X+1) is in a different region. A "?" is a stand in for any digit 1-9.
- Liar X-Sums clues : For each row/column with clues, two clues are provided. Only one of them (top or bottom, left or right) is fully correct. The other clue is lying and therefore totally or partially wrong.
Example puzzle :
Solution code: Column 6, with hyphens (-) for region borders. (Example: 123-45-6-7-89)
Comments
on 10. February 2026, 05:35 by Agent
Awesome! Impressive depth of region-building logic after the clues are used.
on 6. February 2026, 20:47 by MaizeGator
The ?4 clues in R6 were peak Christounet
on 3. February 2026, 02:16 by tallcat
Masterful construction. Very clever use of a relatively sparse number of clues. For a CC, I would rate this a 4/5 difficulty.
on 27. January 2026, 19:19 by protheph
An absolute marathon. Spent more hours than I'd like to admit over multiple days chipping away at this. Hard-earned and incredibly satisfying once the logic clicked. Thank you!
on 25. January 2026, 22:22 by Calvinball
What a puzzle! Had that perfect balance of hard/fair, I never once felt stuck.
on 25. January 2026, 16:05 by henrypijames
Very intricate break-in, and fantastic geometry logic - incredible for anyone's first fullsize CC.
on 24. January 2026, 13:40 by Christounet
Updated Sudokupad link
on 24. January 2026, 13:21 by samuel1997
Is it possible to enable the colouring of the X-sum clues for marking the liars? I found it a little bit too tricky to keep track of the liar clues at the beginning stage. Of course if it is intended, I take it back XD!
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I think I know what you mean. I always set on penpa where this is automatically possible. I will edit the sudokupad link so that the clues can be colored there as well. Thanks for the suggestion.
on 24. January 2026, 13:09 by samuel1997
It's a fascinating puzzle! I especially love the CC part at the very end stage! Thank you
on 24. January 2026, 12:59 by Snookerfan
Incredible and brilliant puzzle! Full of surprising aha moments. The break-in and the first half were quite tricky, after a certain point it became very smooth. Thanks
on 24. January 2026, 11:17 by madhupt
Wonderful puzzle! It’s really surprising how it solves with so few clues. Great fun!
on 23. January 2026, 21:47 by dzamie
The full puzzle is a fair bit too tricky for me, but the 6x6 was a lot of fun!
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Thanks! Glad you enjoyed the 6x6 :)
If you want to try the big one and get stuck, I can provide some hint. Let me know!
on 23. January 2026, 18:03 by marcmees
Sweet little lies. Thanks
on 23. January 2026, 17:00 by Playmaker6174
Very cleverly set puzzle overall! It felt like a two parts solve for me but the regions building part in this one was very nicely done and rather wonderful there (which must've taken ages to find, lul) x)
on 23. January 2026, 16:40 by Qodec
Loved that! Thanks!
on 23. January 2026, 15:14 by Jesper
Fun CC, thanks!
on 23. January 2026, 14:16 by Christounet
Reformulation of the "liar X-Sums clues" definition.
on 23. January 2026, 10:31 by Piatato
Very cool puzzle, thanks!
on 23. January 2026, 09:19 by cyddrdrd
A cool combination with great fun! Thanks :)
on 23. January 2026, 08:49 by Chanome
wait i dont get it.
so for the liar x-sums, does the rule that
the first x cells on that row/column from that direction are in the same grp still apply?
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If the clue is not entirely true, it is considered a liar, but part of it could be true.
