Sudoku Variants Series (449) - Zipper Lines ++
(Published on 7. November 2025, 06:00 by Richard)
I will see how long it takes before I am running out of ideas.
Zipper lines ++
Inspiration for this type comes from RockyRoer.
Solve online in Sudokupad or in Penpa+.
This puzzle can be solved in a complete logical way, but contains a few tricky steps. I have written the full walkthrough as a hidden comment, for learning purposes.
Apply classic sudoku rules.
The sums of each pair of digits coming out from the center (indicated by a diamond) of a Zipper plus line increases by one.
E.g.: if the single center cell contains an 8, the sums of the pairs go up to 9, 10, 11 etc. If the sum of the central pair of digits is 6, the sums of the next pairs go up to 7, 8, 9 etc.
Digits may be repeated on lines.
Solution code: Row 2
Comments
on 18. November 2025, 07:15 by baal
How do I see the hidden comment?
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Reply: Hi baal, I guess you have seen it by now. Hidden comments can be read only by the setter of the puzzle and those who have solved it.
on 9. November 2025, 20:02 by Marshal on Mars
Fun puzzle! Similar to Astral, the last line was where it got difficult for me (rated 4 stars on the basis of that line; the rest I would say is a comfortable 3). I was able to somewhat reasonably work that line down to 3 possibilities, but getting from those 3 to only 1 was fairly tricky.
on 9. November 2025, 08:31 by Richard
Added that the full walkthrough can be read as a hidden comment.
on 9. November 2025, 08:17 by Richard
I have written a full walkthrough for this puzzle for either learning purposes if you needed to guess or confirmation of your solve path if you found all the logic. ;)
on 8. November 2025, 17:59 by Franjo
As the original puzzle is from RockyRoer nobody should be surprised that you have to do some arithmetic exercise. I gave 3* loving the nice deductions here. Thank you very much for creating and sharing another beautiful SVS-puzzle.
on 8. November 2025, 17:21 by Richard
This is one of those types in which investigating what goes on is close to science. At least, it felt so for me when I started thinking about possible entries. There is much to play with in this type, so figuring out all kinds of logic (mainly about odd/even!) was fun. I will write a full walk through for this one tomorrow, so in case you missed something or needed to guess, there is something to learn afterwards.
on 8. November 2025, 09:38 by AstralSky
Everything flowed nicely until I reached the last Zipper line remaining.
Then I encountered a huge difficulty surge and had to find multiple chains to get to the solution.
Not sure if I am missing sth towards endgame
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Yes, you must have missed something. Guessing is NEVER necessary in my sudokus (apart from SVS #147) and also no sophistic moves like chains, wings, jellys and skyscrapers. Just plain sudoku logic and the intrinsic logic of the type.
In fact, it makes me sad IF players need to guess to find the solution and, hence, have less fun in solving.
In this one, finding the last digits can be indeed a bit tricky, but not to a large extend...
on 8. November 2025, 07:27 by Richard
I am surprised about the perceived difficulty of this puzzle. Four stars, and even close to five...
I thought it would be pretty obvious where to start and with only a limited number of zipper lines the rest of the puzzle would flow easily. :-)
After all those years, I find it still very hard to estimate what is and what isn't easy to find for puzzlers.
on 7. November 2025, 16:55 by therealsillypenguin
Amazing break in, and a surprisingly hard middle to end of puzzle. Thanks for sharing!
on 7. November 2025, 15:20 by psninn
beautiful
on 7. November 2025, 14:13 by psninn
beautiful
on 7. November 2025, 10:09 by RebelSystem
That was hard. (At least I found it hard). Fun though and such a relief when the last digits went in and I hadn't messed it up somewhere along the way!
on 7. November 2025, 07:37 by Piatato
Tight construction! Quite tough, yet satisfying to figure out!
