Hidden Serpent
(Published on 21. December 2022, 03:04 by DJV)
Rules
Normal sudoku rules apply.
Normal Fog of War rules apply. The grid is initially covered in fog, except for a single light source. Placing correct digits will clear some fog and reveal more of the grid.
Snake: There is a 1-cell wide snake in the grid composed of orthogonally connected cells, that starts in the circle in r1c1 and ends in another circle in r9c9. The snake cannot touch itself, even diagonally. The snake must visit every box. Digits in squares are not snake, and give the total number of snake cells that are in the surrounding 8 cells. All possible squares are given.
Killer: Digits in cages cannot repeat and sum to the small number in the top left corner of the cage. Digits on the snake do not count towards the cage totals.
Solution code: Row 9, then column 9.
Comments
on 12. June 2023, 06:07 by mayflower
I really enjoyed this puzzle! I am a beginner, and it took me just over an hour, but the logic flowed really nicely and at no step did I feel that I was stuck. Thank you so much for sharing it
on 29. March 2023, 23:51 by Bankey
Enjoyed the puzzle. Though tricky at places, but didn't need to resort to guessing. Thanks, @ DJV :). Keep them coming!
on 7. February 2023, 16:49 by codewizard
I found this both quite easy and really hard. It flowed nicely until it came to box 3/6/9, and I struggled mightily, and in the end I couldn't find a solid logical deduction to resolve it, and I had to resort to an educated "guess" (which was right). I would assume, though, that there was something *I* missed rather than the puzzle being flawed... It had to do with it being very hard to disprove that the cages there could grow and get digits far away. I'm sure one could do it. When discounting (without disproving) those remote possibilities it was pretty straight forward. I could not find a use of the negative constraint, even though I tried hard at that point.
>>It’s not you! The difficulty does indeed ramp considerably at the end, and that’s my fault as a newer constructor at the time. You have to remember that the cage total is in the TOP LEFT corner of the cell, so the cages in box 6 can’t grow upwards. And even then it’s still not straightforward. Thank you for solving and constructive feedback!
-- No, thank you for the awesome work! The point I got stuck was exactly the same as kakstront (hidden comment), and I understand Dandelo's point(s). And I also see in his picture that there was a snake cell that I could/should have placed at that point, which would have reduced the possibilities. Good point about upward growing cages, I don't think I considered that :) These things just make this puzzle even better, and it's maybe just that this step is a bit *unexpectedly* hard (not too hard), and you assume that you've done something wrong or missing something obvious, rather than just accepting the difficulty :)
on 30. January 2023, 04:16 by Calvinball
I wanted to love this puzzle when it came out and struggled mightily with it. I just revisited it with a better understanding of the ruleset and absolutely loved it, once you grasp the rules you realize it's not even super tough.
Thanks for taking your time to set this.
>>Thanks for giving it a second chance! Glad you enjoyed!!
on 23. December 2022, 20:38 by Tank
Nice Concept, love FOW puzzles
on 22. December 2022, 21:58 by Jreg
I'm very glad I took to the comments on this one because the rules don't specify that the snake COULDN'T visit the same box more than once & that's what had me stuck initially. I reckon any path with repeated box visits could eventually be rendered obsolete through logic, but it would've taken way longer to deduce that.
Not to be overly critical, I had a blast solving this!
on 22. December 2022, 09:09 by lars
Very fun puzzle, thank you! I really enjoyed the interplay between cages, snake cells and the fog. The updated rules made me not resort into bifurcations, which made it very enjoyable. I didn't need the fact that the snake must visit every box and I didn't use the last square clue, buy maybe I missed some other case I had to consider. Anyway, thank you for the pleasant time! I'm looking forward to more puzzles like this.
on 22. December 2022, 08:15 by obi
SUCH a lovely puzzle, the best I've done in a while! The negative constraint worked really well. Congrats!!
on 21. December 2022, 21:08 by CaptRob
Very nice puzzle. I got stuck a couple of times but I really like how it finishes. Thanks a lot!
on 21. December 2022, 17:13 by mathpesto
I really enjoyed solving this puzzle and the updated rules is definitely an improvement! There was a nice use of the negative constraint on square, and I liked the idea of snake in a Fog of War puzzle! I only found myself significantly stuck at one point, but it just required a little more thought.
on 21. December 2022, 16:18 by 7aminldn
I think this is a very nice puzzle! Keep up the great work :)
on 21. December 2022, 15:09 by DJV
Changed the link to the puzzle to a version with the updated rules.
on 21. December 2022, 14:34 by DJV
Typo
on 21. December 2022, 14:33 by DJV
I updated the rules to give the location of the end of the snake, which should help narrow down possibilities.
on 21. December 2022, 13:58 by Dandelo
It's a very nice puzzle.
There is smooth solution path without guessing anything. I never used that the snake cannot enter a box twice.
The rules are absolutely ok, IMO.
But this a good example, why FOW puzzles don't fit into the Rätselportal. Anyone can find the solution just by clicking around and guessing. So anyone can rate the puzzle without solving. And it's really nonsense to downvote it because you haven't found the logical solution path. If you haven't solved it, you shouldn't rate it at all.
>>Thank you for your kind words! You make an excellent point that I hadn’t considered about Fog puzzles not fitting here. I will likely refrain from posting them here in the future because of that.
If you are on the CtC or PuzzlePlaza discord, I would be interested in how you logically solved the puzzle if you want to message me (@DJV). Unfortunately, I think the commenters below did have a point, if you draw ludicrously big cages, and I clarified the rules to fix that.
on 21. December 2022, 13:37 by juvopa
I realy love the fog puzzles. I had some problems with the hint that ALL squares are given. Maybe better to highlight the word ALL.
Big thanks for publishing.
>>Thanks for solving and glad you enjoyed! I did make that part of the rules bold on the rules page here, but did not do so on the CTC app. I will make sure I make that clear in the future!
on 21. December 2022, 12:20 by dodomos
I think I skipped a few very important steps in the opening.
The snake condition was not very clear, leading me to consider many times when the snake crossed the same box multiple times.
The killer box is also more complicated under the fog. I considered the possible directions for a long time.
In summary, I cannot accurately judge this puzzle.
>>Thanks for attempting the puzzle! I can now see that an extra rule clarification is necessary to truly make it unique, and I have added that. Hopefully that will help with the solve.
----
When I solved the puzzle again, I found that I could solve it.
True, the puzzle required some thought, but it was definitely not as troublesome as I thought it would be when I first tried to solve it. You only need to think a little to reason.
This puzzle is very good in that it requires the solver to extend his or her range of vision. I will change my rating to something more reasonable.
>>Glad you could solve it! Thank you for the feedback!
on 21. December 2022, 10:09 by thrutch
I think that previous commenters must have missed some logic somewhere along the way. The puzzle flowed very nicely for me with no need for guesswork. Some of the deductions were not immediately obvious, but isn't that the whole point of a puzzle? I don't recall exactly how those 5 and 6 cages were resolved from the initial apparent plethora of options, and this was certainly a point in the solve where I was held up for a while, but there is a logical way through.
>>Thanks for solving and for your kind words! I did think it was logical, but I saw some screenshots on another forum that showed that there are some crazy big potential cages that could allow it to work. I’ve updated the rules to fix with this part of the solve.
on 21. December 2022, 09:46 by 97358 Johnny JLJ
it's very hard and it's not nice at all
>>Very helpful comment, thanks!
on 21. December 2022, 09:05 by GutenTag
I don't usually downvote, but I couldn't get through the mid part where the 5&6 cages have like dozens of possibilities. Even double checked rules and did not see the puzzle mentioning the snake cannot enter a box twice. So I had to resort to guess works to finish the puzzle
Am I missing something, or is the puzzle just broken?
>>No worries about downvoting if you think guessing is necessary. That’s certainly not what was intended! There is a logical deduction with the 5 cage that I relied on, HOWEVER, I saw in another forum that people (correctly, but I didn’t foresee it) are noting that the 5 and 6 cages could actually be enormous and there are ways it could work. I updated the rules to give another piece of information that will help with that part of the solve. Apologies, and thanks for trying my puzzle!
