Wednesday 14 September 2011

Double Trouble #1: Slitherlink and Toroidal Slitherlink

I've always been interested in puzzles that can be solved under 2 different rules. It won't be a regular feature as I don't think I can pull it off every time I try. It's just something I find interesting and sometimes give a go. There's a lot of puzzle types out there that look the same at first sight, so there's enough options for me to try it with.

Rules for Slitherlink

This time it's two slitherlinks. You can solve this puzzle as a regular Slitherlink puzzle. It's not too difficult, but still fun.
You can also solve it as a Toroidal Slitherlink. Here the edges of the grid wrap around on eachother, which turns opposite edges of dots into the same line. This means the loop can run from one edge and continue on the other side.
Not every puzzle type will give the possibility to create a puzzle that is both regular and toroidal. This one works as in runs over the grid lines.


  1. Nice design, but I keep finding multiple solutions for the toroidal.

  2. Are you sure the other solutions don't have 2 loops? Because there's a few solutions that might seem right, but if you track the paths, you'll notice it is actually built up of 2 loops. Can you send me a picture of 2 different solutions?

  3. 2 loops indeed. Did not see the dual loops until your comment and then I took my finger and ran it around. Visually didnt see it due to the toroidal nature. Great puzzle. Thanks, and thanks for the response.

  4. Thanks. It was tricky to see. I figured that might be it as that was such a crucial point when designing. It was somewhat a relief to see that I could force it this way as all the options turned into 2 loops but 1. Otherwise all the effort put into making the outside so that the difference between the two solves instantly became clear would have been for nothing.