What is the hardest slitherlink board you have seen/solved/tried to solve? I've tried googling for some hard ones but came up with simple ones or sites describing what slitherlink even is... So in other words - please provide examples of some hard/hardest boards you know (standard slitherlink rules but it can consist of any shapes - doesn't have to be squares).

  • $\begingroup$ Are slitherlinks with slightly modified rules allowed? $\endgroup$ – Wen1now May 27 '17 at 22:45
  • $\begingroup$ Feel free to post them but partially I asked my question to find out if there even are any really hard boards or if this puzzle is limited in that regard. $\endgroup$ – NPS May 27 '17 at 22:48
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    $\begingroup$ Are you familiar with gmpuzzles.com/blog? They have many slitherlink puzzles, and in general their puzzles posted towards the end of the week are more difficult. This link will show you all of theirs: gmpuzzles.com/blog/category/loop/slitherlink and here are some of the hardest ones: gmpuzzles.com/blog/tag/slitherlink-2+classic+fridaysaturday (not sure how consistently they apply the day of week tags) $\endgroup$ – Eric May 27 '17 at 22:55
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    $\begingroup$ Nikoli also has some devious puzzles at the deep end. There is also a site that gives a weekly gigantic 20x20 slitherlink, but I don't remember the name. $\endgroup$ – greenturtle3141 May 28 '17 at 0:48
  • $\begingroup$ Thx Eric. Although sadly they're not very difficult. Which makes me wonder again if it's even possible to create a slitherlink board that would be a real challenge. $\endgroup$ – NPS May 28 '17 at 9:27

This website has the hardest slitherlinks that I know of: http://kwontomloop.com/puzzle.php

Also, as mentioned in the comments by Eric, https://www.gmpuzzles.com/blog/category/loop/slitherlink/
has really good slitherlinks

  • $\begingroup$ Kwon-Tom Loop kicked my ass. I can't even solve a medium one. :P Finally some really hard ones, thank you! $\endgroup$ – NPS Oct 2 '17 at 15:29
  • $\begingroup$ And the best part is, it keeps on changing :) $\endgroup$ – ABcDexter Oct 2 '17 at 15:30

http://www.janko.at/Raetsel/Slitherlink/index.htm got some puzzles up to 45x31. You can sort them by size (Größe) or difficulty (Schwierigkeitsgrad).

http://www.nikoli.com/en/puzzles/slitherlink/ got some hard ones, but only a few free samples.

https://www.chiark.greenend.org.uk/~sgtatham/puzzles/js/loopy.html can generate puzzles of any size, limited only by your computer's power (and your patience). It also has different types of grids, which can be more difficult.

There is also the In-Out and Colorlink variant

  • $\begingroup$ There's a similar version to In-Out in our local newspaper puzzle page with rabbits outside and cabbages inside or something like that. $\endgroup$ – FreddyFlares May 29 '17 at 10:11

Here are three sites where you can find very difficult puzzles:




If you want to start with the most difficult, try an "Unlimited" at the first site.


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