Eccentric Tales from the Sudoku Circle

The Sudoku circle is filled with many fascinating anecdotes, stories that often reveal the passionate, even obsessive, side behind this "quiet game."

The ballpoint pen, plaid shirt, and gavel in the cover image all have their reasons.

Here are a few intriguing tales about Sudoku:

▸ 1. The "Dignity" of a Top Master: Solving with a Ballpoint Pen

At the World Sudoku Championship (WSC), most players come prepared with several mechanical pencils and thick erasers. But the legendary three-time world champion Thomas Snyder (also the inventor of the Snyder notation method) was famously known for solving puzzles using a ballpoint pen. He was recorded in the Guinness World Records as the "fastest person to solve a Sudoku puzzle."

In a logic-driven community, using a ballpoint pen means "no room for error" and "no guessing allowed." It’s a powerful psychological deterrent, signaling that every move he makes is based on absolute logical deduction—no corrections needed. This "no eraser" confidence is seen by insiders as a master-level performance.

▸ 2. The "Sudoku Addiction" That Frustrated a Judge

In 2008, a major drug trafficking trial in Australia lasted three full weeks. Suddenly, the court discovered that 5 out of the 12 jurors had been secretly playing Sudoku, completely ignoring witness testimonies.

This million-dollar lawsuit was eventually forced to halt and declared a mistrial. The judge was furious, and the jurors' explanation was: "The courtroom debate was too dull; playing Sudoku kept us awake." This scandal earned Sudoku the nickname "courtroom killer."

▸ 3. The "World's Hardest Sudoku" and the Pride of the Logic School

Finnish mathematician Arto Inkala has repeatedly published what he calls the "world's hardest Sudoku" (such as the famous AI Escargot). He claimed these puzzles are extremely difficult, requiring humans to use multiple "trial and error (guessing)" and extremely deep hypothetical reasoning to solve.

This sparked a global "siege" by hardcore logic fans. Many masters worked around the clock, trying to prove that it could be solved without guessing. Eventually, some players managed to solve it using extremely complex logical chains. This process proved that: as long as a puzzle has a unique solution, logic can always reach it—the only question is whether the human brain can compute deeply enough.

▸ 4. The Mathematical Curse of "17 Givens"

In the Sudoku community, there was a long-standing mystery: What is the minimum number of given digits required for a Sudoku puzzle to have a unique solution?

Professor Gary McGuire - Photo Credit: Fergal Phillips/Sunday Times

For a long time, the known minimum was 17. Many tried to design a puzzle with 16 givens and a unique solution, but all failed. Until 2012, an Irish mathematics team used a supercomputer to brute-force prove that:

16 givens cannot form a puzzle with a unique solution.

This became the "bible" of the Sudoku world: if you see a puzzle in the newspaper with only 16 digits, don't doubt yourself—the puzzle must be wrong.

▸ 5. The "Godfather of Sudoku" Couldn't Use Advanced Techniques

Although Sudoku was invented by an American, it was Maki Kaji, president of the Japanese company Nikoli, who made it a worldwide phenomenon. He is known as the "Godfather of Sudoku."

Interestingly, this godfather figure once admitted that he was not a Sudoku master. He preferred naming Sudoku (he coined the name "Sudoku") and insisted that all puzzles should be hand-designed by humans, not computer-generated. He believed that hand-designed puzzles contain "the breath of the author" (for example, numbers arranged in special shapes), and this aesthetic is a timeless talking point between logic-focused players and algorithmic players.

▸ 6. Why Do Sudoku Players Love "Plaid Shirts"?

This is a joke circulating in the community. In photos from early World Sudoku Championships, you'll notice that a large number of top players dress almost uniformly: plaid shirts.

People joke that Sudoku players' eyes have evolved to be sensitive only to "9x9 grids," and wearing plaid shirts allows them to contemplate logical structures even when looking in the mirror. Of course, this is just a humorous self-deprecation of the stereotype of science/logic enthusiasts.

▸ 7. Blindfold Sudoku

Just as chess has blindfold chess and Rubik's Cube has blindfold solving, the Sudoku community also has "blindfold" masters.

A player looks at a puzzle once, then is blindfolded, constructs a 9x9 coordinate system in their mind, and fills in all empty cells without ever seeing the grid again. This requires not only strong logical reasoning but also terrifying graphic memory. Currently, this is considered one of the ultimate challenges for the human brain in the Sudoku world.

These anecdotes reflect the core charm of the Sudoku community: it's not just a number-filling game, but an intellectual marathon about rules, logic, mental toughness, and the pursuit of "pure truth."

Every Sudoku player has their own habits. For example, a programmer friend of mine neither wears plaid shirts nor uses trial and error; he solves with a pencil because "he has no master's dignity to defend." Another friend prefers trial and error because he participates in speed competitions and "not using trial and error puts him at a disadvantage."

What are your habits? Feel free to share in the comments.