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WSC Report

12th World Sudoku Championship
Bangalore, India
October 15th-18th, 2017


The World Sudoku Championship has been held annually since the year 2006. Over the years, the Championship has developed and become the premier platform to acknowledge the top Sudoku solvers of the world.

In 2017, we wanted to bring in some new ideas, and have them along with the Classics and existing variants to provide an exciting and varied Championship that was both fun and challenging as a World Championship should be.

Heading into the Championship there were discussions on what a Sudoku at a World Sudoku Championship should be and should not be. We have always believed that it depends on an author's presentation and most rule-sets can still be used to provide Sudoku variants that test Sudoku capabilities more than other capabilities, but may have a small requirement of other capabilities blended in. Let's get to the rounds!

Individual Rounds

Day 1:

Round 1: Welcome This round consisted of Classics & Variants that were themed around the 12th WSC, India, Bangalore and 2017. Tantan Dai of China finished this round before time, and was the only one to do so.

Round 2: The Duets

This round consisted of 24 variants, presented as 12 pairs which were similar to each other. Kota Morinishi raced ahead in this round, finishing 3 minutes before time and getting over a 1000 points. Qiu Yanzhe of China also finished before time, but had a minor error in one of the Sudokus and had to settle for a score of 983 out of a possible 1000.

Round 3: Two to Tango
This was a Hybrids round, combining two different Sudoku variants and using both their rule-sets. We had a single theme through this round of separating the variant decorations and dividing the grid into two halves in a way, impacting the solving path in interesting ways. Tiit Vunk finished this round with 1 minute to go, and continuing the pattern of the previous rounds, there was only one person scoring more than the perfect score.

Round 4: Where is it?
Session 1 was concluded with this light round lasting 20 minutes, which many solvers finished before time. While the round could technically be a lot of searching, the fact that it was just 6x6, had lesser points allotted, and had allowance of partial points made it a fun round with very few zero scores. Nikola Zivanovic topped this round, finishing an entire 12 minutes before time, but Kota and Tiit weren't far behind him.

Round 5: The Originals
The Classic Sudoku round started session 2, and Tiit Vunk topped the round, getting a perfect score of 350 after finishing just on time, with a few seconds to go. This ended up being a strong score, as his nearby competitors scored below 300 for the round.

Round 6: Think Different
This round consisted of Innovative variants, with ideas from the organizers as well as a few from the Puzzle Innovations Contest held on the WSPC website prior to the event. There were 25 Sudoku variant ideas submitted by 11 different authors from a total of 7 different countries, but only three variants made it to the round. The three were also the winning ideas of the contest:
1. Odd-Even Bridge Sudoku by Akash Doulani (India)
2. Wildcard Sudoku by Hemant Malani (India)
3. Unique Squares Sudoku by Matus Demiger & Blanka Lehotska (Slovakia)
While no one finished this round, Kota came close with a score of 460 out of 500. He topped the round, but his nearby competitors weren't far behind, with Qiu scoring 455 and Tiit scoring 415.

Round 7: Is it a Sudoku?
Circling back to the discussion of what a Sudoku is for the WSC, we had this idea of holding a round full of Sudokus with potentially puzzlish rules but designed to require more Sudoku solving. While Nikola Zivanovic topped the round, his score of 295 was closely followed by a 290 from the likes of Dai Tantan, Hu Yuxuan and Sinchai Rungsangrattanakul who are predominantly WSC solvers. So this round provided a good variety in terms of winners but clearly gave enough for Sudoku specialists to solve too. Among the overall toppers, Kota and Qiu were close to the top score for the round, but Tiit fell behind a little with a score of 215.

From the checking room, thanks for all the creative replies to the question posed in the title of the round :)

Conclusion of Day 1:

At the end of Day 1 this Championship already hinted towards a close two-horse race for the title, with Kota and Tiit finishing the day with just 25 points separating them.

Day 2:

Round 11: All in One
This round had nine Classic Sudokus linked together by a hidden 10th Classic Sudoku. The round had many finishers. Kota topped the round narrowly with a 5-minute bonus, but he had a fellow topper in Ming Letian of the Chinese B team! The two of them finished the round just a minute before seven more solvers finished the round.

Round 12: What is it?
This round consisted of Sudokus without written instructions. They instead had a solved example above using the same rule-set, which was to be deduced by the solver before solving the competition Sudoku. This round has since been held as a contest on LMI, so everyone can try it out and see this different way of solving Sudokus. The round was topped by Qiu Yanzhe who finished with 6 minutes to spare. He was closely followed by Tiit. Kota and Seungjae Kwak also finished the round, but without a bonus.

A fun fact about this round, some of the participants who got zero scores in the Classic round managed some good points here! Who needs instructions, right?

Round 13: The Joker
This round presented a new element within Sudoku solving, taken from the Joker concept used in Playing Cards. All Sudokus had a joker hidden among the digits which could take up any value to satisfy the rules. This was a new concept, so the scores were a little on the lower side. Kota topped the round with a score of 475 out of 600. Tiit didn't do so well, with a total of 370, and the title race tipped firmly in Kota's favour at this juncture.

Round 14: Usual Suspects
This round consisted of the usual variations seen in many Sudoku contests over the years. With Kota in the lead after round 13, Tiit had to present a strong showing - and that's exactly what he did, finishing the round without a bonus, scoring 500, while Kota faltered a little and scored 425. Kota's lead was down to a mere 35 points with two rounds to go.

Round 15: Along the Edges
This round had four Classic Sudokus with clues between them showing the common digits across grids. It was designed to be a finishable round, and many solvers finished before time. The round was topped by Takuya Sugimoto who finished with 13 minutes to go. While Tiit and Kota didn't have as good a showing, they were still close to each other with just 10 points separating them, and Tiit cutting the overall gap down to 25 points.

Round 16: Do Not Blink
This round provided something different, with participants looking at the main screen and determining the correct digit for just one circled cell of each Sudoku. This round had negative points for wrong guesses, which would turn out to be a major factor in the Championship. Qiu Yanzhe and Zoltan Gyimesi topped the round with a perfect total of 150, but the question of the title winner was down to Kota and Tiit. Kota didn't do well on this round with a total of 70 points. Tiit did a little better, enough for a potential 100+ total, but made a mistake which not only reduced his points for correct solutions, but also gave him a negative of three points; the exact gap in the total between Kota and him!

Conclusion of WSC Individual Competition:

In what is perhaps the most closely fought race in years, Kota Morinishi won the title with a total of 4890 compared to Tiit Vunk's total of 4887. This competition and margin will be remembered for years, and the two competitors will definitely not forget it. Qiu Yanzhe had an impressive showing to finish at 3rd place with a total of 4730. It marks the young solver's first podium finish, and it is likely to be the first of many.

The top three A-50 solvers were David McNeill (1), Mark Goodliffe (2) and Michael Smit (3). The top three U-18 solvers were Dai Tantan (1), Hu Yuxuan (2) and Ming Letian (3), continuing the Chinese domination in the age division.

From left to right: Hendrik Hardeman (Special Guest), Tiit Vunk (2nd), Kota Morinishi (1st) and Qiu Yanzhe (3rd).


The team competition rankings are decided with a combination of Team round scores and the sum of scores of the four participants from the team in the individual rounds. Here's how the team rounds went.

Round 8: Yours or Mine
This round involved a simple swapping of Sudokus every 10 minutes between two groups of two teammates each per team. The Sudokus of this round were higher on the difficulty scale than most other rounds, with all Sudokus having only decorations and no given digits. This meant having different sets of eyes on them actually sped up the process, making it an ideal team round. Team Japan and Team China finished the round, with Team Japan finishing a minute earlier for a total of 1360. No other team finished the round, or even came close, so the top two teams established their dominance early.

Round 9: Dress them up
This round consisted of variations which were thought up by Indian authors over the years, but with a twist: The decorations were separated from the givens and it was up to the teams to figure out the correlation before solving each variant. This round proved to be difficult for all teams. Team China topped the round with a score of 780 out of 1400. Team Japan didn't do so well in the round, and in fact fell well short of their own team B's total. Team USA had an impressive showing with a total of 655.

Round 10: The Big Choice
This round consisted of two Samurais (i.e., 5 overlapping Sudoku grids each) where each Sudoku grid could have one of two possible rule-sets and it was part of solving to figure out the correct rules. Team China topped this round too, with a perfect score of 1000, ending day 1 on a high.

Round 17: Sixers
This round consisted of 36 small Sudokus which then had to be placed as elements into a larger 6x6 grid with Sudoku rules and a 'missing digits' rule to facilitate a different way of solving. This round had strict instructions to ensure mechanical solving. Team China topped the round, finishing before time and amassing a total of 2120. Many teams finished this round, and team Japan was close to China but had an error which set their total back to 1999 after partial bonuses.

Round 18: The Journey
This round was picked very early by the organizers to be the culmination of the Championship. It had 24 Sudokus around a central ring Sudoku, depicting the Ashoka Chakra on the Indian Flag, and was also an anthology of variants introduced over the years at WSCs from 2006 to 2017. The setup was completed with 12 Classic Sudokus with themes of 1 to 12, alternating with the 12 anthology variants. Everyone seemed to enjoy this round. The eventual top three teams, China, Japan and France all finished the round, with Japan topping it with a total of 2040. Team Netherlands also provided a good account of themselves, finishing the round towards the end for a perfect score of 1800.

Conclusion of WSC Team Standings:

Like the Individual competition this was always a two-horse race. While Team Japan won some rounds and had a very strong team, it just wasn't enough to stop the excellence of the Chinese team. Team China topped both the team rounds as well as the Individual round summations, and ended up with 23315 points compared to Japan's 22821. Team France finished at a solid 3rd place, with a total of 18337, easily ahead of team USA at 4th.

Content availability:

The contents of the WSC are available on sale to Indian solvers at Rs. 1000 as a PDF collection. To find out more about the process of purchase, please send a mail to
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