Logic Masters Deutschland e.V.

Chaos Construction: Double Internal X-Sums

(Published on 9. March 2026, 03:38 by KNT)

Place the numbers from 1 to 9 exactly once in every row, column, and region. Each region is orthogonally connected and must be located by the solver.

In each clued row or column, exactly two clues are given. One of the clues corresponds to the cell immediately in front of the clues, call the number in this cell X. The other corresponds to the Xth cell in the direction of the clues. Which clue corresponds to which cell must be determined for each pair of clues.

For both of these cells, the number placed indicates the total amount of cells seen from that cell within its region, including itself, where region borders and the edge of the grid obstruct vision. The associated outside clue gives the sum of all such numbers seen. A question mark may be any positive value.

One border is already given.

A 6x6 example is provided:

SudokuPad

penpa+

Solution code: Row 4, Column 5


Solved by han233ing, h5663454, smckinley, Jesper, by81996672, marcmees, MaizeGator, zuzanina, bansalsaab, Fool on Hill, henrypijames, cyddrdrd, sehringdipity, SirWoezel, mse326, Clipper, Isael, MountBecton, ... ch1983, snowbaby, zhugelianglongming, Paletron, wullemuus, Hazem-77, Zzzzz..., Allagem, irq, karlmortenlunna, peacherwu2, elmers, MagnusJosefsson, Nick Smirnov, haoju, Mr_tn, steeto, flatbread
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Comments

on 15. March 2026, 21:23 by tallcat
Took me quite a while to see the entry points into the puzzle but once I found my way in, it unfolded very nicely!

on 15. March 2026, 09:08 by Piatato
Very nice, thanks! Lovely ruleset!

on 15. March 2026, 00:33 by BloodbuzzCorio
Great puzzle KNT! Thanks for setting and sharing.

Last changed on 9. March 2026, 23:47

on 9. March 2026, 23:47 by cyddrdrd
Beautiful and intriguing!

on 9. March 2026, 15:04 by MaizeGator
Interesting break in followed by super smooth mid solve and ending

on 9. March 2026, 14:38 by marcmees
Very beautiful. Thanks

on 9. March 2026, 10:17 by Jesper
Very nice!

Last changed on 9. March 2026, 03:37

on 9. March 2026, 03:36 by KNT
This is an alternative SudokuPad link for those who want to mark the outside clues: https://sudokupad.app/penezv2fks

Difficulty:5
Rating:93 %
Solved:54 times
Observed:2 times
ID:000RSN

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Solution code:

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