Genre Spotlight 25: Diagonal Chains (Puzzles 267 and 268)

Quick post today.  As of writing this, my PhD defense is two (2) days away.  By the time this post is live, I'll most likely be a doctor!  Or something. (Edit: whoops, I forgot to schedule this post for Thursday!  So, uh, you're getting these puzzles slightly in advance.  Tomorrow's post has been moved back as a result.)

On an unrelated note, most of my puzzle energy has been spent preparing for this year's Logic Puzzle Open.  If you're in the United States and would like to meet with other puzzle peeps at MIT in a month, feel free to swing on by!  Several of us have been hard at work preparing for the event, and while we may be slightly tight on time, we'll guarantee a good time or your money back.  (Spoilers: the event is free.)

With that said, on to our regularly scheduled Content.  Today's genre is "Diagonal Chains", a type originating in the Innovatives round at WPC 2019.

Rules: Shade some cells to create diagonal chains. Shaded cells cannot be orthogonally adjacent, and no shaded cell can touch more than two other shaded cells diagonally. Furthermore, there can be no 'loops' of shaded cells – in other words, each group of diagonally connected cells must have at least one shaded cell with less than two diagonally touching shaded neighbors.

Cells with numbers cannot be shaded.  The numbers indicate the sum of the lengths of all such chains where at least one shaded cell is horizontally, vertically or diagonally neighboring to the numbered cell.

            

Genre Spotlight 24: Santoitchi (Puzzles 265 and 266)

This will be the last Inaba genre for now.  I've found several hidden gems within the collection (including one that I'm saving for something more official!), but in general, his more obscure genres are difficult to construct puzzles for.  Today's style was no different -- individual clues often aren't powerful by themselves, but every clue taken together creates a powerful effect, so you really need to carefully choose the numbers to make the solve work.  That said, today's puzzle might actually be my favorite of all the Inaba types so far.  Each clue can only see a limited distance away, but the interactions are more subtle than you might think.

This genre is sometimes called "Sandwich" by English speaking sources, bu that name is a bit silly, so I've chosen to go with its Japanese name "Santoitchi" instead.  Apparently, "san to ichi" translates to "three and one" in Japanese, which fits the rules better.  I don't know where the extra t came from, but oh well.  Blame Google Translate.

Rules: Shade some cells so that no two shaded cells are orthogonally adjacent and divide the remaining unshaded cells into three-cell regions. Each region must contain exactly one numbered cell, which indicates how many shaded cells the region is orthogonally adjacent to. 

          

Genre Spotlight 23: Remaze (Puzzles 263 and 264)

I've noticed that all three Inaba genres so far have been loop/path puzzles.  Naturally, some people might want some variety.  Here's your variety: have a maze genre instead.  Totally different, I swear.

Rules: Draw some borders to form a maze. The maze has two exits as indicated. The maze cannot contain any cycles, and all cells should be reachable. The maze doesn't have any 4-way intersection.

Each O indicates a 3-way intersection, and all intersections are marked. Each X indicates a dead end, and all dead ends are marked. The unique path through the maze passes through all intersections.

             

Genre Spotlight 22: Spur Loop (Puzzles 261 and 262)

Next on the list is Spur Loop.  I suspect this genre is more common than the other two, but "maze"-like puzzles are not quite as popular as they used to be.  Spur Loop reminds me of Ring-ring a lot, to the point where I think a doppel between the two genres should be doable.

Rules:  Draw a crossing loop passing through all cells.  Each segment of the loop must have length at least two.

                  

Genre Spotlight 21: Move Data (Puzzles 259 and 260)

Next up in the Inaba backlog is another genre with a simple ruleset: Move Data.  This genre uses Tapa-style clues, but was invented four years earlier!

Rules: Draw paths through the centers of cells such that each path starts from a shaded cell and all cells are used by a path. Paths may not cross each other or themselves. Clues represent the lengths of the line segments appearing along the path, not necessarily in order. Each number is used exactly once in its path.

         

(The half-length segments aren't required for answer check here; I just think they look nice.)

Genre Spotlight 20: Long Ring (Puzzles 257 and 258)

For the first time this series, I'm writing this post after the previous one has released 😧.  Turns out that writing a thesis saps your energy toward other things, who would have guessed?  Fortunately, the dissertation is now done, apart from some administrative minutia and, well, defending the thing.  My current plan is to run through a few Inaba genres for now to clear out some of the backlog.

Today's genre is Long Ring.

Rules: Draw a loop along the grid edges.  Numbers indicate the length of the line the circle is on. 

Yep, that's the entire ruleset.  Classic Inaba, eh?

           

Genre Spotlight 19: Raneko (Puzzles 255 and 256)

Today's puzzle seems to be an somewhat recent Nikoli type, debuting in issue 166.  I'm unable to find any instances of this puzzle online, other than listings on Cross+A and janko.at, and one grid in the GAPP series.  It's a neat type, combining region division with Minesweeper-style clues.  (Though these only count orthogonally adjacent cells rather than diagonally adjacent ones, so maybe they're actually Koburin-style clues?  Shrug.)

Rules. Divide the grid into regions of orthogonally connected cells. Each region must contain exactly one circle. A number in a circle indicates how many cells are in the region the circle belongs to. A black cell is not part of any region, and indicates how many different regions it’s orthogonally adjacent to.

I'm using the Nikoli example grids here, which are lower-quality images but showcase the fact that the genre was originally constructed with cat symbols instead of circles.  Everyone must know this vitally important information.

            

Genre Spotlight 18: Gardens (Puzzles 253 and 254)

It's always surprising to see what niche puzzle types lurk in the depths of the internet.  I found Gardens tucked away in janko.at, attributed to a German puzzle designer named Uwe Wiedemann.  It's a cute type.  It combines Nurikabe with Shikaku to get a puzzle that, while not as expressive as either original genre, still has some interesting interactions.

I've modified the presentation slightly to change it from a "regions" genre to a "shading" genre.

Rules: The diagram contains small gardens, i.e. rectangular green areas separated by hedges (shaded cells). Number clues cannot be shaded, and every garden contains exactly one number equal to its area. Each 2x2 square must have at least one garden square.  Gardens may touch diagonally.

                 

Genre Spotlight 17: Haisu (Puzzles 251 and 252)

As of the time of writing, Haisu is about eight years old and has a dedicated puzz.link interface, but has yet to branch out into the general puzzle contest world (apart from a few appearances in 24HPC).  That's quite surprising!  It's a very natural idea that can lead to fiendishly difficult puzzles, so you'd think puzzle constructors would latch onto it as quickly as possible.  But maybe that difficulty has turned people off.  It certainly did for me at first.

Rules: Draw a non-intersecting path through the centers of all cells, starting from the S (start) and finishing at the G (goal). Each clued cell must be traveled through on the path’s Nth visit to the region the clue lies within, where N is the value of the clue.