Tuesday, 20 October 2026

Director - World Sudoku Championship 2026

One fine evening while we were speaking on a call, Amit & Prasanna mentioned that I should take the role of Director for the World Sudoku Championship 2026. While they had already thought about it, it came out of blue for me. I was definitely happily surprised but more than that nervous. My first response was that I need them to be there to guide me throughout which they obviously agreed to. With this one phone call, I was the Director of the World Sudoku Championship 2026!


It was a once in a lifetime experience to take up this role.

This year as we aimed to have an overarching theme of Mahabharat, it started with planning the theme for each and every round and putting the themes into a rough structure. For some rounds it was a broad theme idea but for some we engineered the rounds in a way that the layout and the structure of the sudokus were also adapted to the theme. For example, for the first round Kuru Clan, we took the theme of the Origin of the Pandavas and the Kauravas and chose the variants which reflect the Origins of Sudoku. But for the round Draupadi’s Swayamvar, we curated a Flower Sudoku and connected it with 5 Pentagram Sudokus. For Gandhari's Solidarity, we had the participants blindfold themselves in honour of Queen Gandhari. These ideas took long discussions of exchanging ideas, building upon each other’s ideas and thinking what can / cannot work in a contest setting.

Gandhari Round


Parallelly, we onboarded a team of 11 authors who crafted the sudokus for the championship. When the authors came in, we started the process of authors claiming the sudokus they wanted to create and discussed the theme ideas for each and every sudoku where we could put a theme. Each sudoku submitted went through a rigorous process of testing which included testing the difficulty level, the thematic representation and the appropriateness for a World Championship. There was one more layer of decision once all sudokus for the round were created – how difficult is the round as a whole coming out to be. We wanted each round to have a right mix of sudokus with a range of difficulty so that there was something for everyone to solve in each round and no round was designed only for the top solvers. I am happy to share that across Individual and Team rounds only 4% of the participants scored a zero on an average.  

In this process of creating sudokus and working with other authors, I learnt something very new. While I had collaborated with authors to create sudokus for a contest earlier where we had split the responsibility with each one creating some sudokus, I had never worked on a single sudoku with other authors. This time I got to do this as well. I remember one particular sudoku where Madhav created the sudoku, I modified it a bit and Madhav modified it a bit more and eventually we had a sudoku which was set for WSC.

The process of discussing sudoku ideas, testing them, discussing how we can make each sudoku better and more interesting was a learning experience on its own. Every author had some brilliant ideas and when we exchanged these ideas, we sometimes reached something even better.

After the first level of testing, the next step was to create booklets and send them to testing by many testers including both Indians and International testers. When it is about creating booklets, LMI has always relied upon the expert – Deb – who created the booklets this time as well. For the Individual rounds, we shared the booklets with all the testers. Generally the feedback from the testers was good – they liked the sudokus as well as the theme. But there were two concerns – the total solving time was coming out to be longer than what we ideally wanted it to be and some of the sudokus were too difficult for the contest. Additionally, there were few new variants which we had introduced where the rules were confusing. Considering all the feedback we decided to drop a total of 13 sudokus which brought everything into place. We also refined the wordings for the rules for a few more sudokus.

Parallelly, there was also a process of preparation and testing for the Instructions Booklet (IB). There were many new variants for which we had created example sudokus. Each of these sudokus was also tested by a team of testers. Based on the feedback from these testers we made changes to ensure that they reflect the rules for sudokus in the actual competition, the IB sudokus are also unique and have a good solve path.

And there was one additional parallel flow – testing the team rounds. The team rounds were tested by Indian testers in many cities. Some of them got tested when we met in August at the Indian Sudoku Championship; some others were tested in Mumbai and few in Bangalore.

The testing feedback for an event of the scale of WSC includes feedback such as the shade of gray in one sudoku is not exactly same as the other one, the thickness of a line is different, the IB sudoku does not have a closed loop but the competition puzzle has and so on. Incorporating each and every feedback and getting to a stage where all booklets are perfect is a task much bigger than you can imagine!

Then came the process of deciding the duration for each round, the points for each sudoku, the bonus points for each round. We wanted to have a mix of rounds – some finishable by many solvers and some finishable only by a few so that every level of solver enjoys the rounds.

Director, World Sudoku Championship 2026


Fast forward to the day of the World Championship! Standing on the stage in front of 153 participants from 32 countries was a moment which I can never describe in words. It is a memory which will live alive in front of my eyes always and forever! When each round started on time, ended on time, whenever a participant shouted “Finished!”, when we were able to complete checking a round on time, when I rushed to a participant to write down their bonus time, when I saw participants enjoying the team rounds, when Tiit Vunk – 2x World Sudoku Champion – told me that the quality of sudokus this year was one of the best in the last 5 years, there was a wave of dance inside me (though I looked anxious until the last round came to an end)! Being the Director of the World Sudoku Championship was a feat I never dared to dream but proudly lived!

Tiit's Feedback


Ofcourse, the role of being a part of core organizing team came with many other responsibilities apart from the role as WSC Director. Getting to work for an event of this scale was an experience in itself.

I was happy to have locked in two major sponsorships this year with Matiks as the Title Sponsor and Rodha as the sponsor of Team India. For many years since Covid, we did not have any sponsor for sudoku & puzzles in India and WSPC was the best chance to get sponsors on board. We were able to get few sponsors on board and get a huge media coverage.

I also worked on many other aspects in capacities big and small – from helping with designing the standees (which came out as the life of the event hall), to co-ordinating with transport vendor for airport transfers, to curating a plan for excursion to looking at many many other small bits, it was an great time!

Group Photo


And lastly, the great team I got to work with! A team which included experienced organisers to first time volunteers, experienced sudoku authors to first time authors, people from every major city of India but who had one common goal – to bring the event to life! The journey was never a smooth ride. Thousands of issues came up along the way but we stood together as a team – a team which was ready to literally spend many sleepless nights to drive the event. And we did it!

Signing off as the Director of World Sudoku Championship, 2026!    

Tuesday, 1 September 2026

Sudoku 102: Windoku

The rare occasion when I remember I have a blog to post to😜

Windoku
Rules: Apply Classic Sudoku rules. Additionally, each marked 3x3 region contains each digit from 1 to 9.
Links:

Saturday, 11 April 2026

Sudoku 101: Encaged 4 Sudoku

Sudoku GP Round 4 has started and it features a new variant - Encaged 4 Sudoku. Posting a practice sudoku. 

Given it is one of the mid-pointers in the round I expect the contest sudoku to be easier than this one. Nonetheless, I hope you enjoy solving this sudoku. 

Encaged 4 Sudoku
Rules: Apply Classic Sudoku rules. Additionally, the digit 4 may only be orthogonally adjacent to odd numbers. 
Links: 


Sunday, 27 July 2025

Milestone Sudoku Contest: Winners!

Drumrolls!πŸŽ‰

A big congratulations to the winners of the Milestone Sudoku Contest!

1st - Aashay Patil (with an impressive timing of 61 minutes!)

2nd - Kishore Sridharan

3rd - Tushar Maheshwari!

Thank you all for participating in the contest. Hope you all enjoyed solving the sudoku :)

If you did not get a chance to solve the sudoku, do give it a try and let me know how you find the sudoku. 

Lastly, once again a big thanks to Nityant Agarwal for test solving the sudoku. 


Saturday, 26 July 2025

Sudoku 100: Milestone Sudoku Contest

It's time for the first contest of the blog! You must solve the sudoku and mail an image of the solution to hemantkr97@gmail.com. The first 3 participants to share the correct solution will win Amazon Gift Vouchers! Let's Go!

Rules: Classic Sudoku rules apply. Additionally, some of the boxes have a few decorations. The decorations in each box have been taken from a sudoku posted on the blog earlier (different sudokus for different boxes). The decorations of all forms (line, circle, square, shading, etc.) have been converted to shading. If a box contains decorations, all digits in that box will be exactly same as the sudoku from which the decorations have been taken. It is a part of solving to determine the sudokus from which the decorations have been taken.

Links:

Tuesday, 22 July 2025

Milestone Sudoku Contest

It's time for the 100th sudoku and the first contest on the blog!πŸ’₯

The sudoku (along with the rules) will be posted on the blog at 1 pm IST on 26th July, 2025. The solver has to solve the sudoku and email an image of the solution to hemantkr97@gmail.com. The first 3 solvers who submit the correct solution will win gift vouchers!

A big thanks to Nityant Agarwal for test solving the sudoku. 

Please note that you might require 10-12 sheets to solve the sudoku. A4 sheets should suffice. If there are any questions, please feel free to reach out or comment here. 


Wednesday, 16 July 2025

Sudoku 99: Little Killer Sudoku

 

Hello! Posting the 99th sudoku on the blog with the theme 99. 

A special announcement - the 100th sudoku on the blog will be a contest! The sudoku will be posted on 26th July at 1 pm IST. The first ones to solve will have the chance to win exciting prizes! Stay tuned for further details!
Little Killer Sudoku
Rules: Apply Classic Sudoku rules. Additionally, numbers with arrows indicate the sum of the numbers in that direction.
Links: