Sunday, March 10, 2024

Puzzzle 209 ("One of Each", Pentominous)

It's been a bit since I've posted here.  Most of my puzzle writing energy has been directed toward this year's edition of the Logic Puzzle Open (which will be taking place in a month, aaaaaaaaaaaaaa).

In the meantime, have a Pentominous puzzle.  The last time I posted one of these was way back in early 2022, more than two years ago!  The improvement in my construction ability should hopefully be pretty clear.

Online interface ( 

Wednesday, January 31, 2024

Puzzles 207 and 208 ("Diagonal Streaks", Yajilin)

Last night I constructed two Nikoli-style Yajilin puzzles.  The 17×17 was constructed first, while the 10×10 was added later.  This pair emulates willow's style, who will always post puzzles in pairs (one smaller, one larger).  I don't expect to continue following this pattern, but it is an interesting idea.

Smaller puzzle interface (


Larger puzzle interface ( 

Sunday, January 21, 2024

Puzzle 206 (Ant Mill)

I wrote this puzzle almost two months ago and completely forgot about it!  This genre is quirky but pretty neat.

Rules: Shade some dominoes of cells.  No two dominos may touch orthogonally, but each domino must touch exactly two others by the corners such that all dominoes form a single loop.  Cells separated by a square must both be shaded or both be unshaded.  Cells separated by an X must not (i.e. X marks overlap exactly one shaded cell).

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Monday, January 15, 2024

Puzzle 205 (Numberlink)

Another Numberlink, this time monster sized!

I originally used pzprrt to attempt to prove uniqueness as always, but after 4+ hours of running it had yet to find a second solution.  (My original attempt was non-unique, and pzprrt took 2 hours to find a second solution.)  After posting the puzzle on PuzzleSquareJP anyway, someone linked me to this program.  It's an incredible solver, somehow claiming uniqueness in only an hour!  Given how old the program is I'm surprised it's not more well-known outside Japan.  Maybe that's because nobody in the west constructs Numberlink puzzles at the rate Nikoli does.

Pzprrt is probably more convenient in most cases because its implementation makes up for the time it would take to input the solution into the above external program.  But it's nice to know that constructors have been using programs for 15 years to verify uniqueness; it makes the constant output from Nikoli make more sense. 

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Sunday, January 7, 2024

Puzzle 204 (Numberlink)

It's been a while since I posted here.  Have a Numberlink!  This was also posted to PuzzleSquareJP.

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Friday, December 15, 2023

Puzzle 203 (Choco Banana)

I found out today that the Choco Banana I submitted to the WPC got reprinted in the most recent Nikoli issue, which I'm ecstatic about!  To celebrate, here's another puzzle.  It has a slightly tricky break-in but should be smooth sailing after that.

Online interface

Sunday, December 3, 2023

Puzzle 202 (Guide Arrow)

Hey, it's been a while!  I've been posting some puzzles on PuzzleSquare JP lately rather than here; feel free to check them out!  This change may or may not be temporary.  I know some users like bakpao and Eric used to have both official blogs and twitter feeds which housed different kinds of puzzles; it's possible I'll do the same thing here.

That said, I do want to cross-post one puzzle to this blog as well.  A few days ago I went back to the tilted square theme with Guide Arrow.  I thought a long time ago that constructing a 13x13 version of the theme would be almost impossible because the arrow clues were too far apart.  It turns out I missed a few possible break-ins that would have worked, and I eventually came up with a puzzle.  

Then I became ambitious and decided to see if I could make one with a 'hollow' square, rather than a 'filled in' square.  Somehow, the answer is "yes".  

This is definitely a step up in difficulty from my other Guide Arrows, but I still can't believe it's unique.

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