Friday, 3 December 2021

Puzzle 360: Killer Sudoku

I'm sure this sort of thing must have been tried before, dearest reader.  Not my most elegant work, but the vast majority of the windows will need to be opened if you want to make it through to the end.  Enjoy!
    #360 Killer Sudoku – rated 6/10 [Hard]
All puzzles © Tom Collyer 2009-21.

Thursday, 2 September 2021

Puzzle 359: Heyawake

It's been a long time since I did Heyawake.  As with the recent Masyu, it's not entirely Nikoli smooth, and there are bits I'd even go so far as describing as fiddly, but hopefully it makes for a decent challenge at least.

As a bit of an aside, I came across recently, and lots of it basically seems like magic to me.  For example:
There's also something called pzprRT, which seems like an extraordinary setting tool.  Basically, for a small number of types, including 4 of my favourites: Yajilin, Masyu, Slitherlink and indeed Heyawake, you are able to mark up your puzzle using the pzprjs project (i.e. as featured on and then you can press a button and it will give you the live deductions corresponding to the clues you've put in.

I am still generally avoiding marking up my puzzles using, as the interaction between the puzzle player and the hidden database (which stores the metadata of logged in solvers) is still not entirely clear to me.  I think I saw that this metadata is indexed by hashed versions of the puzzle URLs rather than the URLs themselves - this would kind of be fine by me I think as it means the database would be genuinely only metadata, rather than actual puzzle data making up some kind of secret dystopian mega master puzzle database.  But in any case pzprRT generated me a, so I think it means this puzzle is now on the database, hashed or otherwise, and now what’s done is done.

I suppose what it does mean for you, dearest reader, is that you can also play along online!  I may even start making a habit of it.  Enjoy!
    #359 Heyawake – rated 8/10 [Very Hard]
All puzzles © Tom Collyer 2009-21.

Sunday, 22 August 2021

Puzzle 358: Masyu

So I don't think this is really as smooth and polished so as to live up to Nikoli standards, but there are a couple of flashes of something here and there to keep you interested, dearest reader.  Enjoy!
    #358 Masyu – rated 6/10 [hard]
All puzzles © Tom Collyer 2009-21.

Saturday, 21 August 2021

Puzzle 357: Sudoku

I'm going to be posting a few Nikoli style puzzles over the next few days.  I was about to say that there probably won't be any Sudoku, but that's not entirely true.  As a bit of a preview, there will probably be a few Renban Groups that I'll post, mainly because I've seen too many examples where the groups are presented as lines, rather than shaded regions, and it's annoyed me past a critical point.

Anyhow, puzzles like these I guess aren't as common as they used to be.  Nothing too flash here.  Enjoy!
    #357 Sudoku – rated 3/10 [Easy]
All puzzles © Tom Collyer 2009-21.

Tuesday, 17 August 2021

Maki Kaji

I saw in the news today that Nikoli president Maki Kaji has passed away at the age of 69.

I had the chance to meet him at the 2010 world sudoku championships, hosted that year in Philadelphia, USA. Always fond of games and gambling - Nikoli the puzzle company takes its name from Nikoli the racehorse - he hosted a couple of rounds of the Nikoli derby in which I was lucky enough to finish to second, winning a tenugui which I still have with me today. 

(Thanks - in advance! - to Przemysław Dębiak for the photo)

Kaji was known as the “godfather of sudoku,” following his role in the worldwide explosion of its popularity in 2004.  

I am tickled to see an example of a Masyu puzzle included on the BBC website (and also how much better designed it used to be!). But I come under the category of a puzzle fanatic. I think part of his puzzling greatness is reflected in this quote:
"The secret to inventing a good puzzle," he said, "is to make the rules simple and easy for everyone, including beginners. 

"You have to be able to make both easy and difficult puzzles using the same rules.

"Between 200 and 300 people help to complete a new puzzle. It has to be something that children, old people and everyone in between can enjoy, to be really good."
Rest in peace. 

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