# Puzzle 203: Slitherlink [just one segment]

It’s always fun to figure out some new arguments in a puzzle type. While going through @taburega’s tough puzzles, I ran into one occurrence of a pattern I didn’t know before, and recently managed to distill it into something a bit more memorable while finding some similar arguments in a kwontomloop.com puzzle.

I’m curious how well known these techniques are, let me know! I hope to follow this up with a discussion of the “theory” at some point.

Rules This is a Slitherlink puzzles with many solutions, all of which share one segment. Find that segment.

# Puzzle 202: International Borders

Here’s a sample for another new type on puzz.link: International Borders by Palmer Mebane; the implementation was contributed by Lennard Sprong. This is probably not the most gentle introduction to the type.

Rules Shade some cells to split the grid into edge-connected areas of unshaded cells (“countries”), one for each color ocurring among the clues of the puzzle. Clues are unshaded, and each country must contain all clues of the corresponding color. (Uncolored clues may belong to any of the countries.) Clue numbers count how many of the four adjacent cells are shaded. Furthermore, every shaded cell must be a border cell: it must have at least two unshaded cells that are part of different countries.

# Puzzle 201: Aqre

I was introduced yesterday to this great type due to Eric Fox of f-puzzles, and decided to go ahead and add it to the puzz.link applet. Here’s one:

Rules Shade some cells, so that all shaded cells are connected by edge. Clues indicate the number of shaded cells in a room. There can’t be more than three shaded or unshaded cells in a row, i.e., no I-tetromino can fit fully inside the shaded or unshaded cells.

# Kangaroo Star Battles

Some more of my puzzles are up now over at mathe-kaenguru.de. This time, it’s a set of 6 Star Battle puzzles (as well as a tiny puzzle by Bram which probably slipped in along with the applet). The puzzles are listed under April 1st; there’s also a print version.

# puzz.link update: New pzprjs release, and introducing network play

Big new feature on puzz.link: You can now solve puzzles together. Just start network play via “File -> Network play” and share the link. It’s quite experimental and likely flaky, but already so much fun that I decided to share it now.

Otherwise, there’s been countless changes since the last update, which I’ve wrapped up in version 0.13.0. Besides various bugfixes and improvements (see the full Changelog), we have a couple of new puzzle types: Araf, Balance Loop, Doppelblock, Maxi Loop, Mid-loop and Simple Loop.

I made some puzzles for the German maths kangaroo prize booklets a while back. Today, they put a set of Slitherlink/Fences/Rundweg puzzles online as part of their offer for kids who are currently staying home due to the virus. You can solve them, too: https://www.mathe-kaenguru.de/zuhause/

# Puzzle 197: Nurimisaki

Following up the previous Cave, here’s a tougher Nurimisaki. Once you’re comfortable with the type, it might not qualify as “hard” anymore, but if not it will sure feel like it.

That puzzle type switched back to being a shading-first puzzle; I had previously made it an “unshading-first” puzzle for autocheck, but I’ve since changed autocheck for (some / most) shading puzzles to require all cells to be decided before triggering, so the major downside of shading-first is gone.

# Puzzle 196: Cave

Here’s a little cave I made to illustrate a downside of my recent change to switch the puzz.link solver back to “shading first” for Cave and Nuri-Misaki.