The Tenth Box: Unboxing
(Published on 10. May 2026, 00:21 by Liamhere)
Rules:
Normal Sudoku: Fill the grid with digits 1–9 such that every row, column, and 3 by 3 box contains each digit exactly once.
The Tenth Box: The nine center cells of the standard 3 by 3 boxes form a "Tenth Box" which must also contain the digits 1–9 without repetition.
Any rule or constraint in a standard 3 by 3 box is applied to the corresponding cells in the Tenth Box. Constraints map from the nine standard boxes to the Tenth Box, but not vice-versa.
Killer Cages: Digits in a cage must sum to the value in the top-left corner. Digits cannot repeat within a cage.
German Whispers: Adjacent digits on a green line must have a difference of at least 5.
Kropki Dots: White dots separate consecutive digits. Black dots separate digits in a 1:2 ratio.
Inequalities: Digits separated by an inequality symbol must satisfy the inequality (the open side points to the larger digit).
Example: In this puzzle, the first two cells in Box 1 are inside the cage of sum 10. This means that the sum of the digits in cells R1C1 and R1C2 is 10. Furthermore, the sum of the digits in the first two cells of the Tenth Box (R2C2 and R2C5) is also 10.
Solution code: Column 7 (top to bottom)
Comments
on 18. May 2026, 11:29 by Liamhere
Updated rules on sudokupad link
on 14. May 2026, 23:54 by firespire
Helps to do the later easier Tenth Box one first as an introduction.
on 11. May 2026, 02:57 by Liamhere
Thanks
on 10. May 2026, 21:37 by pjot
I loved the Tenth Box rule and I would very much appreciate more 1-2 * puzzles with it. Thank you for this one!
on 10. May 2026, 10:14 by Liamhere
Added clarification on rules
on 10. May 2026, 09:51 by keenbowl
I've tried to understand the Tenth Box - Every constraint mirroring rules for about an hour now, but I'm drawing a blank, all interpretations I've tried don't seem to work.
But I guess I will accept I'm just not smart enough for that rule.
Edit: This is a bit embarrassing, but I did have the right interpretation of the rule, only did my brain too often jump into a V mindset although there is no V rule, only inequality....
For those who still are confused about the phrasing of the rule:
There are 2 distinct box-patterns of constraints, and both also apply to the Tenth Box itself.
Then it really was a quite nice 2*-puzzle, thank you for setting and sharing (and also for adding the example)
