Modular Fortress
(Published on 31. January 2026, 01:00 by yttrio)
Rules:
Normal Sudoku rules apply.
All lines are both modular lines and fortress cells.
Modular lines: Each set of three adjacent digits along a line must be one each from the sets [147], [258], and [369].
Fortress (maximum cells): Cells on a line must be larger than all orthogonal neighbors of the cell that are not on a line.
Solution code: Row 9
Comments
on 1. February 2026, 21:08 by Black_Doom
What a gem of a puzzle! Seems impossible at first, but a few very simple, yet very careful questions break this one open.
on 1. February 2026, 17:06 by Wuschel
Very nice, thank you!
on 1. February 2026, 16:56 by zeniko
Elegantly minimal setting, leading nonetheless to some nice interactions. Thanks for sharing.
on 1. February 2026, 13:17 by Firebird
Miraculous and beautiful!
on 1. February 2026, 04:16 by Crusader175
Fun puzzle!
on 31. January 2026, 17:07 by Prince Joffrey
very elegant
on 31. January 2026, 14:18 by Franjo
Thank you very much again for creating and sharing another astonishing beauty.
on 31. January 2026, 12:42 by Snookerfan
Great puzzle! Had me baffled for a while, thanks!
on 31. January 2026, 08:06 by Piatato
Fun!
on 31. January 2026, 06:49 by Allagem
A surprisingly beautiful puzzle that seems intimidating at first but becomes a joy to solve once you find a foothold. I loved it!
on 31. January 2026, 02:20 by antiknight
Cool combination with unexpected deductions at the start! Harder than the 1st one tho :)
