Puzzles #681, #682 & #683 - More Showcase Backlog (Kurodoko, Tapa-Like Loop, Rail Pool)

Continuing the backlog, these were some of my entries for The Sixty Second Logic Showcase, where the prompt was to make a good puzzle that the median solver would take... sixty seconds on. I'm really happy with everything I made for this showcase, but in hindsight I should have attempted a more scattershot approach for estimating timing, as I misjudged where the median would be. All of my estimates were spot on relative to each other, but they were also about 50 to 60 percent longer than I had guessed, from assuming a larger overlap with logic race. Due to the combined scoring on votes and timing, and the timing component being a quadratic decay instead of a linear decay like I had misread, I placed very poorly in the final rankings despite doing pretty well in the unranked votes only ranks.

Anyway, onto the puzzles I submitted that I have one version of!

I started with a Kurodoko with what I hoped was an interesting logical theme. From my own timings I expected to hit about 1:10 with this which was close enough, but ended up at 1:50, and multiple people mentioning they got stuck after a couple opening steps. Unfortunate.

puzz.link interface

Since I thought that might be a bit long, I originally tried to aim smaller and stick to that logical theme idea with a 9x9 Tapa-Like Loop. 9x9 quickly didn't work for the theme I was going for, but loop puzzles can be speedy, so I was fine with going 11x11 if I thought the solve was straightforward. This one ended up being the closest to a minute timing-wise, but was still an overshoot.

puzz.link interface

My last puzzle and again an attempt to go easier was a 62 themed Rail Pool. This was the puzzle I was the most off-estimate for, since it's a less common type and thus the median solver has to take longer to find more common steps. I don't think it's a coincidence some of the closest puzzles were extremely common types, but again I don't regret trying something a bit more out there. Perhaps I should have gone even further in the obscure direction and made a 7x7 or something? Somehow, this is the first time I actually made a Rail Pool, too.

puzz.link interface

Puzzles #658 & #659 - 24HPC Domino Kurodoko

I also contributed several puzzles to the Puzzlers Club rounds at the 2024 24 Hour Puzzle Championship this year. We authored two rounds, each with 24 puzzles. The first round had one puzzle themed on each Greek letter, while the second round was a double zodiac (signs and animals).

Very early on I grabbed Beta and made a variant Kurodoko where instead of shading single cells, you shade dominoes instead. This variant does result in a bit of struggle for uniquely specifying the orientation, and can also sometimes have long-term propagations that break the puzzle way in advance. I'm pretty happy with how this 40 point puzzle turned out. I also wrote an example for the type, since it wasn't a classic type.

puzz.link interface      penpa interface

puzz.link interface      penpa interface

Puzzle #599 - Eraser (Kurodoko)

My intended break-in for this Kurodoko turned out to be imagined, though the puzzle is still unique, and the layout is still striking. No point wasting the puzzle (though it could no longer be used for its original purpose), so consider this a warning: this is probably about a 3 on the Toketa scale, with some mix of pencils and erasers. If I had to pin it down, 2 and 1?

puzz.link interface

Puzzles #556 & #557 - Broken Dynasties (Statue Kurodoko, Domino Context)

Recently - and by recently I mean nearly 3 months ago by the time of posting - I submitted 2 puzzles to Puzzlers Clue Logic Showcase 46, with the prompt of taking a "dynasty" genre and changing only the rule about shaded adjacency. "Dynasty" is the jargonistic term for a structure where shaded cells may not be adjacent and all unshaded cells are connected. I actually submitted with first Kurodoko Statue Park about 90 minutes after the showcase prompt was posted, and it ended up being a tied win! Clues act as Kurodoko clues, and the shaded cells must form exactly one instance of each of the twelve pentominos as in Statue Park.

puzz.link interface      penpa interface

I'm pretty sure this puzzle is unique without the 5s on the right side and possibly without the 7 at the top, but since puzzles are meant to be solved... it makes a much better puzzle to not require ridiculous packing steps.

I also made a Domino Context, where the only rule change is that all shaded groups are dominos instead of monominos. This one ended up in 5th (behind two Menderbug puzzles with the same number of votes, losing the tiebreak to Menderbug as I voted for 2 puzzles instead of 3) which is pretty respectable. I think any of these could have ended up winning and honestly, that this variant is more interesting than the base genre.

puzz.link interface      penpa interface

Puzzle #483 - Just 4 Fun (Kurodoko)

I'm back.

Sorry about the 5 months of inactivity, I had always intended to post my modest backlog of puzzles after Secret Solver (you'll see why) and also wanted to have a small series leading up to puzzle 500. And as part of that leadup, I had wanted to share the puzzles I made for friends who participated in Yajilin Yacht. Yes. That Yajilin Yacht from July/August last year. I kept getting sidetracked but I'd already made the plan and I elected to stick to it, because how long would making 5 more puzzles take? How long would making 3 more take? Apparently, the answer was months and months. Sorry guys, but I did at least get everything out, and now it's time to catch up.

I made this Kurodoko puzzle quite a while ago to show a fun deduction with 4s, and it seems like a pretty good puzzle to start back on.

puzz.link interface

Puzzles #445 - 448 - IPC 2022 Round 1 (Sashigane, Kurodoko)

I was fortunate enough to be offered the opportunity to contribute to and testsolve for the 2022 Indian Puzzle Championship. The first round was for puzzle types that appeared in the years Puzzle Ramayan series, and I made a Sashigane and a Kurodoko worth 20 and 40 points, respectively.

puzz.link interface

Wait, hang on, that was the first attempt at a fairly easy Sashigane. It didn't resolve super nicely so I tried again.

puzz.link interface

Nope, that wasn't it either. Though I'm mostly happy with the symmetric theme and lack of numbers, it's not really a competition puzzle, you know? Glad I made it, but I had to try again.

puzz.link interface

There we go. An 8 clue, one per row and column Sashigane. Pretty sparsely clued for the type and some neat logical steps along the way resulted in a puzzle I'm really happy with as a low point contest puzzle.

puzz.link interface

As for the Kurodoko, my first attempt at making a puzzle I liked was a puzzle I liked. I've always had a particular affinity for these two genres and was glad to get the chance to make these.

Puzzles #391 - 400 - MadMahogany's Christmas Tree Conundrum (Shading and Sudoku Medley)

Like the last two years, I took part in the Secret Solver event on Puzzlers Club. This time around, I got MadMahogany, someone I mostly know is semi-active (I think?) on the CTC Discord, and some of their most memorable puzzles they've posted to their blog have been shading or sudoku puzzles. Sudoku is obviously outside my general comfort zone, but whatever, this was the perfect opportunity to go big and make something incredible. So I made a Samurai Sudoku shaped like a Christmas tree with different variants in each subgrid. Rules after the puzzle images.

penpa interface

Nurikabe | Tasquare | Canal View | Nuribou | Nurimisaki | Kurotto | Mochikoro | Cave | Kurodoko

I also decided to make a collection of 5x5 shading puzzles themed on 12/25 (as close as I could get it) for each shading puzzle variant in the big puzzle. Rules for Nurikabe, Tasquare, Canal View, Nuribou, Kurotto, Kurodoko, Nurimisaki, Mochikoro and Cave can be found linked here, as well as Sudoku. These 9 puzzles were a last minute addition when I finished with time to spare, and I thought it would be nice to have a brief reminder / demonstration of the shading rules before having to dig into the tree itself.

"penpa" link (the URL is too long for some browsers, so go to Penpa, select "Load" from the top bar, and paste the URL from the pastebin into that box to load the puzzle)

So, here's the tree. Standard rules apply for each puzzle type within each labelled subgrid. Some grids overlap: the contents must satisfy all rules from both grids when taken only for that grid. As an example, Kurodoko requires shaded cells to not be adjacent to other shaded cells. This rule only applies within the Kurodoko grid, and so a shaded cell on the edge could be adjacent to a shaded cell in another grid. Any cell with an outlined gray circle will have its value act as a clue for the shading puzzle in that grid. Note that most thermos and arrows have the circles coincide with shading clues, but not all. A rundown of each variant rule follows. Star Battle - 1s and 2s may not share an edge or corner with each other. Thermo - numbers must strictly increase from the circle to the end. Arrow - the sum of all numbers on the arrow must equal the number in the circle. Classic - no additional restrictions apply. XV - Cells separated by a V must sum to 5. Cells separated by an X must sum to 10. Cells separated by an XV must sum to 15. Not all Xs or Vs are given. Kropki - Cells separated by a white dot must differ by exactly 1. Cells separated by a black dot must have one number be exactly double the other number. Not all dots are given. Difference - Cells separated by a red dot must have a difference of the number inside the dot. Killer - Cells inside a cage must sum to the value in the cage, and must not repeat within a cage. Product - Cells separated by a pentagon must have a product of the number inside the pentagon.

This puzzle took me probably 30 hours across several weeks to construct, and I got to work with a couple rulesets I'd never worked with before. Like overlapping grids (somehow this was new to me- many headaches from contradictions across grids though...), most of these number placement variants (Arrows are a huge pain, and Killer is way harder than I thought it would be), and Mochikoro and Canal View (fun and easy, painful and difficult. Though some of the Canal View pain was from the other restrictions, it's hard to make unique!). Special mention goes to the Nurikabe for being an absolutely massive gigantic pain to make unique, and the Cave, and the Kurotto section, and generally huge parts of this puzzle barely work. But it all comes together beautifully and I'm very proud of what I came up with here. And my solver liked it, too. :)

I'd also like to take this space to thank Rever for testsolving most of this puzzle before I sent it out, Swaroop for updating Penpa to even support grids this big, and djmathman for making the gift I received, which is really quite excellent.

That's all for now, sorry about the inactivity here, more puzzles soon once I write up the posts for them because I have another 8 waiting already. Errata: added a white kropki dot I thought was unnecessary, but was made necessary due to a bad deduction in completely different section.

Puzzle #137 - Distant Pairs (Kurodoko Loop)

So, after I made my first Kurodoko Loop puzzle, I knew I wanted to try to make another one. So I set out on this fairly ambitious and sparse theme, to exploit just how strong the Yajilin constraint can be. There's one step here that's kind of mean, but the rest is completely fair.

puzz.link interface           penpa interface

I would definitely recommend solving in penpa here- it supports all three of shading cells, drawing lines, and drawing lines over clues which no puzz.link interface does. If I've set this up correctly, there should be a notification when you've solved correctly there, too!

Puzzles #130, #131 & #132: Kurodoko Trio

So it turns out I've now solved every Kurodoko on puzz.link except one. Here's three more I made, all inspired by either things I found in solving, or musings about the genre I had. No bifurcation is necessary and the logic is well worth discovering, here!

puzz.link interface

This first one is probably the most difficult of the three, but also my favorite.

puzz.link interface

Likely the easiest, but a pleasant solve from those who tested it.

puzz.link interface

The idea in this third puzzle can definitely be used for some more interesting or complicated deductions. It turned out exactly how I wanted it to in the end, though.

Puzzle #129 - Three's Company (Kurodoko)

I've been solving a lot of Kurodoko lately.  One puzzle had a simple yet surprising interaction that led me to explore more complex interactions, and this was the result.

puzz.link interface

Thanks to edderiofer, lovemathboy, SoftFro and Plurmorant for helping to test-solve this and ensure that the intended logical step is required.

Puzzle #126 - Where is Black Cells? (Kurodoko Loop)

A couple days ago I had the idea to try to make a Kurodoko and Yajilin hybrid puzzle, themed around one specific break-in. Unfortunately, it didn't seem to work out too well but I did find that the combination had some fun constraints and made this puzzle after the failed attempt.

puzz.link interface        empty yajilin interface
penpa interface (full support)

I'm as surprised as you are that this works. Solve as a normal Kurodoko puzzle. Additionally, draw a loop through all unshaded cells. Alternatively, solve as a normal Yajilin puzzle, where each number must "see" exactly that many cells (including itself).