Monday, October 19, 2020

Would you believe it? It has been more than four years since last I shared a puzzle here. Not that I stopped making puzzles, mind you - I have been contributing to sudoku magazines, competitions and more - but circumstances forced me to take a break with puzzlemaking during the fall of 2016, and I simply never found the motivation to resume my activity with the blog. My life was hectic back then - it still is - and forcing myself to make puzzles every week could not fit in it, and still cannot. For nearly four years I focused on making a living out of selling puzzles (with limited success), and it is only recently that I felt ready to try something new.

Following the postponement of the World Sudoku Championship 2020 and encouraged by the success of the now world-famous Youtube channel Cracking the Cryptic, I recently tried my hand at making sudoku videos with a focus on speedsolving, since there were almost no such videos available anywhere and I felt like I could fill this gap efficiently. I currently release between one and two videos a week on the Youtube channel 81 Cells, and at the moment this is the best place to follow me. I also do livestreams occasionally, on Twitch rather than Youtube since the Twitch interface is infinitely more friendly for this purpose. The Youtube channel is where you want to go to watch spectacular solves of spectacular puzzles, while Twitch streams are meant to be a bit more casual and informative - at least they should be once I manage to grow a bit of an audience... and to fix some unfortunate issues with my Internet access.

Seeing how my previous attempt at sharing sudoku-related content once a week ended, I cannot say for how long I am going to keep this going; but I feel like this is as good a time as any to try. Of course the core of my professional activity remains puzzlemaking, but hopefully this will help me find a balance between the crafting and solving halves of my passion for sudoku.

I have not planned to resume publishing puzzles here on a regular basis, but I might share one once in a while. I am going to publish one right now, at the very least. Be warned: though a most common variant, it is rather on the tricky side of the difficulty scale! It comes in two versions, the original one and, purely for the sake of it, a second one that is more visual. Pick the one you prefer. Here are two links to solve the puzzle online using the F-Puzzles interface designed by Eric Fox: ("minimal" version) ("elephant" version)

Finally, here is a link to Simon Anthony's solve of the puzzle on Cracking the Cryptic:

Rules :
Each row, column and region must contain the digits from 1 to 9.
The value on the top-left corner of a dotted cage is equal to the sum of its digits. No digit can repeat within a cage.

#190 Killer Sudoku


Monday, October 31, 2016

11e Championnats du Monde de Sudoku et 25e Championnats du Monde de Jeux de Logique

À l'adresse des personnes peu familières de la langue anglaise, un compte-rendu en français agrémenté de nombreuses photos est disponible sur le site

Le site étant en cours de construction, il est possible que l'adresse change au cours des prochaines semaines ; je remplacerai bien sûr le lien si tel est le cas. Bonne lecture !

Thursday, October 27, 2016

11th World Sudoku Championship and 25th World Puzzle Championship - Part 2

Then came the puzzles. There is not much to say here, at least regarding my performance; since I did not want to risk making my injury worse, and as I barely had the time to read the instruction booklet before the competition, my intention was to play even more casually than I usually do - and yes, as it turned out, it was possible. Contrary to sudoku, I could not solely focus on the hardest puzzles since there were many of them I would probably never have been able to solve. I picked puzzles somewhat randomly, made tons of mistakes despite my slow pace, and ended up with what was (I guess) my worst result at a WPC, but that was to be expected.
On the other hand, the team rounds went just fine; of course we did not do anything great in terms of score but we all had a really good time. I even got an occasion to shine with my one-man solving of the Double Block in round 16... on which we brilliantly managed to swap two "3" stickers, awarding us with 0 point.

Regarding the overall results, Endo Ken was first after the preliminary rounds with a solid lead on Ulrich Voigt and Palmer Mebane. And by "solid", I mean that he crushed the competition until this point; it was really impressive. Unfortunately for him the finals can bring their share of surprises, and the very first puzzle (Coded Nurikabe) got him stuck for more than enough time for Ulrich and Palmer to get past him. In the end, it was yet another crowning for Ulrich, followed by Palmer and Ken, with Philipp Weiß as a somewhat unexpected number 4. Congrats to the four of them.
Also, a special mention to our own Olivier Garçonnet who made it to the under 18 play-offs and got himself a bronze medal. Way to go!

Now for a few words about the championships from a broader perspective.


To say things as they are, I am having a hard time finding something that did not go as smoothly as possible. Zuzana Hromcová did a terrific job as the head of the organising team. The army of volunteers were prompt and efficient, marking was done in a very reasonable amount of time and for the first time, online results were available as the competition was going. I know that was appreciated by people who followed the WSPC. Queries were treated efficiently by Peter Hudák and the group of judges and was there some urgent matter to discuss, it was fairly easy finding someone of the organizing team. Also, I should mention that each and every volunteer was not only efficient but friendly and doing their best to help when needed, which is to be saluted. Hats off!


For having solved quite an amount of slovak sudokus and puzzles (although not that many in the past two years), I thought I had a good idea of what to expect, i.e. a good variety of rather easy puzzles, nicely made and with quite a lot of original ideas but rarely striking in design. Well, I was completely caught off guard by what Matúš Demiger and his co-authors had done. I was absolutely not expecting a round such as the "Basics" one, and several sudokus had me surprised by the thought that had gone into making them. They were still mostly on the easy side but, regarding their quality, definitely on par with what had been done the previous years.

Additional thoughts

There were several innovations this year; one of them being that tons of additional awards/prizes were given during the ending ceremonies. There was one for guessing who would end at the 11th in sudoku and 25th place in puzzles, one for the worst writer (won by my teammate Olivier Garçonnet, who looks like he will be a great successor to Timothy Doyle in this category), and many more. All in all, it was funny and made the ceremonies more light-hearted than usual, which I enjoyed.
On the evening, some more events were organized such as a "Pyjama Sudoku Contest" and a Team Competition. I did not take part in many of them unfortunately, since I was trying to get all the rest I could to make my arm better; but the echoes I had were all positive.
Another thing the slovak team added was team play-offs. Well that was, in my opinion, the best part of the competition. It was really, really good and from a player perspective I dearly wish we will see some more of these. The puzzles were nice, the difficulty was spot-on, and there was just enough tactical planning involved to make things exciting while still consecrating the best sudoku-solving team. Also, it was much less stressful than the individual play-offs where you know you have only yourself to rely on and cannot afford a single mistake. I am glad I stayed in the A-team so that I could take part in this.

I could go along but that's enough typing for today. I will complete this or post another message if I find some more matter to discuss tomorrow.

If not, see you next year in India!

Wednesday, October 26, 2016

11th World Sudoku Championship and 25th World Puzzle Championship - Part 1


A week. One full week of puzzle solving. And once again, it is as if it ended before it even started.

From the 16th to the 23rd of october, more than 300 puzzle and sudoku enthusiasts gathered in Senec, Slovakia, for the 11th World Sudoku Championship and the 25th World Puzzle Championship. Most of them I already knew, and most of them I had not seen in a year - same old recipe since 2011 and my first participation. But unlike the previous editions, there was a tiny difference this year: I had injured my right forearm just one day prior to my venue, and it looked quite bad as it was far from certain I would even be able to play.
After having done my best to use my arm as little as possible during sunday, I went to bed with very few expectations since my state hadn't changed a bit between morning and evening. On monday morning things were slightly better though, and I was able to hold a pen but at the condition that I would stop every couple minutes at most to let my arm rest, and so on. I did what I could, but after the first couple rounds it was clear that this was not the year Tiit and pals would have to worry about me.

That being said, I was still able to play. The situation being what it was, I decided to focus on harder sudokus to minimize the writing I had to do, and to use as little pencil marks as possible. My playstyle, if I may say so, has always consisted in making as little use of pencil marks as possible, so it wasn't really a big deal - and since I prefer harder sudokus... well, you get the idea. The difference was much more noticeable on the sprint rounds (of which there were quite a few, unfortunately) than on the longer ones where I managed to perform honorably. The second day went about the same way as the first one, not great but good enough that I would still be able to bring some points to the team, my primary focus.

I would not have bet a cent on it but as it appeared when the results were published, I had (barely) managed to make it into the top 10 and, more importantly, we were standing at the fourth place as a team - which meant I would soon have to take part in two play-offs.

The individual finals went as expected. Ahead of me were Qiu Yanzhe (China) and Hideaki Jo (Japan), and I was to start right before Jakub Hrazdira (Czech Republic). I knew I had very little chance to catch up with the first two in my current state, and indeed Hideaki was the one to make his way to the second round. Despite messing up royally on a Palindrome Sudoku, erasing it again and again (which my arm did not thank me for), I still managed to finish second from the round, hence ending at the 8th place. More than satisfying, since 48 hours ago I was considering resigning from my A-team spot!

In the end, and despite Jakub Ondroušek having been very impressive during the rounds, Tiit Vunk clinched victory and earned a long-time deserved world title. Jakub got Silver and, unsurprisingly, Kota Morinishi completed the podium.

Meanwhile, Qiu Yanzhe had had his revenge by taking the crown in the under 18 category, with Chen Shiyu earning Silver and Sun Cheran Bronze. The finals were extremely tensed and it was obvious that all five contestants were doing their absolute best, so I believe Hu Yuxuan (4th) and Dai Tantan (5th) deserve congratulations as well. The Chinese team did shine bright this year, as well in results as in their attitude.

The over 50 category saw Zoran Tanasic (Serbia) crush the finals despite starting in third place, and beating Mark Goodliffe (United Kingdom) who had been easily dominating the competition up to this point. Third was Taro Arimatsu from Japan.

Then came the time of the team play-offs. There was Japan, there was China, there was Czech Republic... and then there was us, France! There was no wonder we were overmatched (after the preliminary rounds we were standing at a modest 17k when the other teams were over 20k), but at least we had made it to the finals and we didn't have anything to lose. The format of the finals was a Weakest Link, meaning all four members of each team would have to solve two puzzles individually before they would be allowed to the team table and given a fifth of a Samurai Sudoku (the fifth - central - puzzle would be waiting for us on the table). There, our task was to reconstitute the Samurai and solve the whole puzzle. There was strategy involved, as it was necessary that the four players would reach the team table at some point in order to complete the Samurai; hence Timothy and I were given the - supposedly - hardest sets, which included a Little Killer Sudoku and a Fortress Sudoku, so that Yannick and Olivier would have an easier time going through their own sudokus and we would all meet at the table at around the same time.

Things didn't go exactly as planned but eventually the four of us were standing around the table, struggling a bit to build the Samurai, until we finally figured the correct layout. We went on a rush to solve what was left of the puzzles... then got interrupted by applauses as team Japan had completed theirs and taken the third place. Czech Republic earned the gold, and China was a good second.
Fourth once again, but with nothing to be ashamed of. All three of our opponents had a fantastic team composition (all four players of China-A were in the top 12!), and considering we started with a 5 minutes handicap on team Japan and would have needed about 2 to 3 more minutes to finish the Samurai... well, between 20:30 and 21:30 on the 18th of october 2016, we were actually faster than team Japan. Well worth the trip to Slovakia!

And that's it for today. Soon, a few (probably short) words about the WPC, and an overall review of the week.

Pictures are courtesy of Théophane Garçonnet.

Wednesday, September 14, 2016

Grille de la semaine #174

The last variant from this series is a fairly easy Extra Regions Sudoku. This one should not give you too much trouble, unless maybe you have never seen such a puzzle. Good luck, and have fun playing.

Règles :
Chaque ligne, colonne et région, ainsi que chacune des régions grisées, doivent contenir les chiffres de 1 à 9.
Each row, column and region, as well as each of the shaded areas, must contain the digits from 1 to 9.

#189 Extra Regions Sudoku


Wednesday, September 7, 2016

Grille de la semaine #173

The rules of Sudoku 6 Parmi 9 come from my fellow french player and author Sylvain Caudmont. They are a great twist to the original sudoku rules and allow the creation of really tough 6x6 puzzles. This one in particular isn't devilish but should still keep you busy for a little while, although there are ways to get around the intended path.

Règles :
La grille comporte 6 chiffres différents à déterminer entre 1 et 9.
Chaque ligne, colonne et région doivent contenir les chiffres en question.
De plus, le nombre en haut à gauche d'une zone délimitée correspond au produit des chiffres de cette zone.

Use a set of 6 different digits amongst 1, 2, 3, 4, 5, 6, 7, 8 and 9.
Each row, column and region must contain the digits of the set.
The value on the top-left corner of a bounded area is equal to the product of this area's digits.

#188 Sudoku 6 Parmi 9 Product


Wednesday, August 31, 2016

Grille de la semaine #172

Medium-hard sudoku this week; again, this Pointing Evens Sudoku comes from the French Selections 2016. Considering it was the least solved sudoku variant on the whole event, it may have been a little underestimated. What do you think?

Règles :
Chaque ligne, colonne et région doivent contenir les chiffres de 1 à 9. Les indices à l'extérieur de la grille correspondent au nombre de chiffres pairs dans la diagonale indiquée par la flèche.

Each row, column and region must contain the digits from 1 to 9. Clues outside the grid correspond to the number of even digits in the diagonal indicated by the arrow.

#187 Pointing Evens Sudoku