Empty entropy
(Published on 22. July 2026, 09:05 by Lithium-Ion)
Normal sudoku rules apply. Each row and each column acts as an entropic line. Any sequence of 3 digits along an entropic line must have a low digit (123), a medium digit (456) and a high digit (789). Within each box, the box number x has to be placed in a cell with a position index that is at most x. Boxes and position indices within boxes are numbered in normal reading order. For example, the cell in row 2 column 7 has position index 4 within box 3. Cells that are diagonally adjacent along a positive diagonal (i.e. a diagonal going from south-west to north-east) contain digits that differ by at least 3.
You can play this puzzle via the following link: https://sudokupad.app/wl9ng58o2c
Solution code: The digits in row 9, read from left to right.
Comments
on 22. July 2026, 22:08 by Macarena
Simple, but very beautiful construction. One of my favourites, loved it. The solving path is so clean and smooth. Incredible
on 22. July 2026, 15:06 by baltoguy
Very cool puzzle. @Fisherman begs the question of diagonal roping
on 22. July 2026, 11:49 by Lithium-Ion
@vukkarak: I am sorry that along "a positive diagonal" was misleading for you. This rule affects each positive diagonal, not only the main diagonal. I thought that writing "a" instead of "the" was clear enough, but I am happy to hear to you figured it out by yourself.
on 22. July 2026, 10:55 by vukkarak
I first thought it is really just the main positive diagonal, then realized that is not enough. Still after that I was struggling to prove the obvious. So maybe it was just my mistake.
on 22. July 2026, 10:46 by RailMan
Very nice and fairly approachable puzzle.
on 22. July 2026, 10:32 by XhcnoirX
Very, very cool! Yes, if you 'see' it, it's a very quick 1* solve, but it's still a highly enjoyable one.
on 22. July 2026, 09:47 by Fizz
That was really cool!
