Cracking the code: Chennai's sudoku enthusiasts solve their way to global puzzle community

CHENNAI: Ashish Kumar is always up for a challenge. With roots in Rajasthan but born and raised in Chennai, his corporate life was just like many others - unfulfilling. Realising that his true calling lay elsewhere, he chose to return to his family's stainless steel raw materials business.

Ashish was 22 when he stumbled upon the world of Sudoku in 2014. “I started solving and creating Sudoku at the same time. I would stay up the whole night and keep solving,” he recalls.

His interest soon led him to competitive puzzling. Ashish discovered the World Sudoku Championship (WSC) and World Puzzle Championship (WPC), two arenas where the sharpest minds from across the world compete. In 2016, Ashish got selected for the B team (an unofficial team) from India which participated in the WSC and WPC in Slovakia. By 2017, he was part of the WSC and WPC held in Bengaluru, a seven-day event that had more than 30 countries participating. “Hosting the World Championship in India was indeed a proud moment,” Ashish says.

From rails to rows

‘Chennai Puzzlers’ run by Ashish Kumar started off as a WhatsApp group that gives a platform for enthusiasts to share their love for Sudoku, exchange puzzle-solving tips, and assist each other with challenging grids.

The community members are anything but typical. Among them are K Ravichandran and Kumaresan R, two loco pilots who developed a love for solving number puzzles.

It began as a serendipitous journey in 2011, when Ravichandran’s curiosity was sparked when he bought a newspaper for just Re 1. “News didn't pique my interest. I kept flipping through pages to discover two sets of classic Sudoku.” This curiosity soon turned into a habit.

Kumaresan, now 54, got captivated by the grids in 2006 by a fellow loco pilot. “I have always had an interest in mathematics,” he recalls. “I was good with numbers in school, though grammar was never my strength.”

The turning point for Ravichandran, also 54, came when he participated in his first Sudoku Championship in Chennai where he competed against 600 participants and came 12th. Quite invigorated, he returned the following year. “When they were announcing the third place, little was I paying attention until Kumaresan nudged me,” he recounts with a chuckle. That performance earned him a spot at the national level.

Though Kumaresan participated in various championships, he often found himself just short of the podium. Not one to be discouraged, he took the route of puzzle creation. “I realised I can contribute by designing Sudoku variants, which are as challenging as solving them,” he says.

He creates Sudoku for Grandmaster Puzzles, a website which promotes logic puzzles made by the best puzzle designers from around the globe. “Doctors in the US recommend Sudoku for Alzheimer's patients. Among the puzzles that they work are some of my creations.

These two senior loco pilots often try taking time out of their hectic schedule for a friendly match. “After our shift, we meet at our resting area in the MGR Chennai Central railway station, where we spend at least 10-15 minutes discussing Sudoku,” shares Ravichandran.

Solving Sudoku has given them both a sense of accomplishment. “It is like piloting a train—every puzzle has its challenges, and every solution feels like reaching a destination.”

Chennai’s own chapter

Numbers have always fascinated Punit Tiwari, who teaches chemistry at one of the branches of Aakash Institute in Chennai. A native of Rajasthan, Punit was part of the Delhi Sudoku community until last year. After relocating to Chennai, he went on an intense scout and found Chennai Puzzlers.

“Let me be practical. Sudoku is not everybody’s cup of tea. There will only be a selective few who choose to solve a Sudoku puzzle during their free time or take it up as a hobby.” Hence the need for a like-minded puzzle solvers community.

“I was taken aback seeing how the community in Chennai is barely active. The Delhi and Mumbai community has over 100 members who hold monthly meet-ups and activities,” Punit adds.

The Chennai Sudoku community consists of only 14 active members. “During the regional Sudoku championships that we used to conduct in Chennai before the pandemic, we used to get more than 200 participants. But they never became regular community members,” adds Ashish.

Through their limited yet tightly knit community, Chennai Puzzlers aim to encourage young minds to inculcate the practice of solving puzzles. “We are reaching out to schools in the city, urging them to incorporate puzzle solving so that the kids can develop into grandmasters,” Kumaresan says. But they have often dismissed the game, failing to recognise its cognitive benefits.

Asian Sudoku Championship

Logic Masters India (LMI), the Indian representative of the World Puzzle Federation, has been conducting national championships since 2008 to select the Indian team for world championships.

As a member of LMI, Ashish has been gearing up to organise as well as prepare himself for the Asian Sudoku Championship, which is set to take place in Chennai between January 18 to 20.

Sudoku finds a different level of respect in countries like China, where it is incorporated into the school curriculum. Not surprising then, that China dominated the recent World Sudoku Championship.

“The top three positions were claimed by Chinese players, which included a 11-year-old prodigy who is ranked seventh globally. These players are my biggest competition,” Ashish grins with a calm, yet competitive spirit.

How to solve the mystery

For those passionate Sudoku solvers, it goes far beyond mere numbers. It’s a fusion between patterns, logic, and intuition, a process that transforms a grid of numbers into a stimulating intellectual adventure.

The core of the experience lies in the pattern. Unlike computer-generated Sudoku which lack depth and structure, handcrafted ones tell a story. "Classic Sudoku is the most familiar format- a 9x9 grid requiring every row, column, and the 3x3 boxes that it contains within should have the digits one to nine without repetition,” Ashish starts to explain.

The variants come with additional rules, infusing a breath of mystified freshness into the traditional format. He adds, “In the diagonal variant, the two main diagonals of the grid must also contain the numbers one to nine. This seemingly simple rule drastically changes the solving strategy, adding layers of complexity.”

In international competitions, only about 20% of the puzzles are classics, the remaining 80% are variants. This mix ensures that the solvers are engaged throughout the event.

Decoding a Sudoku starts with an analysis of density. Sharp minds check for rows, columns, or boxes that are densely populated with numbers. It allows for the best opportunities to place numbers.

"I always start with the densest areas. If I find a number in one row, I immediately scan connected rows or columns to deduce other digits. This approach builds momentum, creating a logical path to completion,” Ashish explains.