Easy Peasy Sudoku Advent (18) - Snake
(Published on 18. December 2025, 06:00 by Richard)
This sudoku advent calendar contains 24 variants that were included in my Sudoku Variants Series (SVS) but turned out to be too hard to be solved by a wide range of puzzlers. I aim for difficulties of 1-2 stars and have written some general and/or specific hints as well. I hope some players will try the original SVS puzzle #147 after solving the advent version.
Snake
Specific hint for this puzzle:
The placement of the 8 in box 6 forces the circle to be the 1. The placement of the 4 in box 3, the 2 in box 4 and the 3 in box 5 indicate the first movements of the snake.
Apply classic sudoku rules.
There is a one cell wide snake hidden in the grid with head and tail on the grey circles. The snake wriggles horizontally and vertically through cell centers and doesn’t touch itself, not even diagonally. It has the form 123456789123…9; starts with 1 and ends with 9.
Use the fact that the snake may not touch itself!
Solution code: Column 2
Comments
on 20. December 2025, 15:33 by henrypijames
@ProcrastinationQueen: I too often use the solution check on the first digits I put in so as to confirm that I've understood the rules correctly!
on 20. December 2025, 04:41 by Piatato
I for one prefer there not being solution check, as I think it very slightly cheapens the experience when there is one. Solving a puzzle feels all that much better when the stakes are a little higher.
on 20. December 2025, 04:07 by Decapod
I hate puzzles without solution checking. I solved it anyway just so I could reflect this in my rating.
on 20. December 2025, 04:03 by ProcrastinationQueen
For the easy advent series, I think solution checking would make the puzzles more accessible. When I do a variant sudoku of a variant I have not encountered before (like this one), it helps me check for the first few steps if I understood the rules correctly. While the hint helped me enough in this one, I just gave up on cold arrows because I couldn't be sure I understood the rule ¯_(ツ)_/¯
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Reply: thanks for your comment. I have let my mind go over the solution checking issue in the past few days, and what you describe is one of the reasons why I have decided to provide links with solution checking for the last five calendar puzzles. As an experiment.
on 19. December 2025, 06:11 by henrypijames
I like solution check. But I think it should be the author's choice whether to include it in the puzzle. I'm slightly less likely to take on or keep working at a puzzle without a solution check, but if the author is okay with this consequence then I am too.
on 18. December 2025, 23:46 by AshBrown
Nice easy snake. Deffo don't need solution checking on for this.
on 18. December 2025, 23:15 by SennyK
Nice and easy, thank you!
on 18. December 2025, 19:08 by dzamie
I usually struggle with snake puzzles, but this was actually incredibly easy!
Tossing in my 2 cents, I'm more likely to actually keep solving a puzzle if I know I went wrong seven filled digits ago, rather than "sometime in the last hour." However, I'm also okay with approaching hard puzzles with the knowledge that there's a good chance I'll have to come back to it another day, if at all.
My favorite method, although not really applicable to most of your puzzles in particular, is with shading/chaos construction puzzles, where the solution code includes non-digit information such as "row 6 with a - to indicate region barriers" or "digits in shaded cells from rows 3 and 4." It makes it more bearable to backtrack after a mistake, but also means that you still can't solve the puzzle if you don't really understand the logic.
on 18. December 2025, 10:33 by knightry
That's pretty silly, to be honest. Solution checking adds accessibility to those who want it, and takes away nothing from those who don't want to use it. But suit yourself.
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Reply: I think my puzzles and sudokus are designed in such a way that you can place every digit or do every eliminiation with certainty, such that you don't need to check if you did it right.
I certainly don't want to encourage 'solving' a hard puzzle by checking with every digit if it's correct.
But maybe for these easy puzzles in the Advent Series, it can be different. I have planned to ask for feedback after the series is finished, at #24 next week. I am curious what kind of feedback that provides.
I also come from an era where it was normal to print out puzzles and solve them on paper. I am in charge of our own national sudoku championship and there it is still the habit to solve on paper too. Maybe there is a correlation with that too.
on 18. December 2025, 09:14 by JVA
Very nice puzzle. I had to read the hint to have the confidence to place 19 in both circles :P
on 18. December 2025, 08:04 by TeddieMilo
I normally avoid "loop" puzzle, but this one is easy and made it really enjoyable. tq!
on 18. December 2025, 07:09 by Piatato
Lovely!
on 18. December 2025, 07:02 by Richard
Added a few words to the instructions to make it more clear. Thx wuc!
on 18. December 2025, 06:56 by wuc
Great snake puzzle. Maybe add a „moves orthogonally through centers of cells“? Nice solve path.
on 18. December 2025, 06:17 by Nylimb
I was worried when I saw this, because I've never made much progress on #147. But this was indeed very easy, as advertised. Thanks!
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Reply: I can imagine your worries. :)
To be honest, SVS #147 is the one I am the least proud of. As soon as it turned out that most players needed to guess in that one, I had in mind to make another one of that type, but it simply didn't happen yet. So when I thought about this calendar, Snake was the first one on the list (although the original has a 3-star difficulty rating and most other SVS's that are included in the calendar have 4 or 5* difficulty.)
I don't expect new solves on #147 anymore...
