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.