What is Sudoku? History and variants of the game

What is sudoku - Sudoku Meaning

A Sudoku puzzle is a partially completed grid with only one unique solution possible. It is a logic-based game in which you insert the numbers 1-9 into each row, column, and six 3×3 square spaces, within a 9×9 grid. The complicated part? You cannot repeat the numbers.

Sudoku puzzle game has gained popularity since its invention by Howard Garns in 1979. It was originally known as Number Place. The modern-day puzzle derives its name from the Japanese term Sūji wa dokushin ni kagiru, which means a single number. In this article, we take you back to the origin of the puzzle and various sudoku variants.

History of Sudoku

Sudoku dates back to the Latin Squares, a Swiss mathematician’s game of the 18th century. The games initially appeared in French newspapers in 1895. The modern version of the game is an invention of Howard Garns, an American puzzle inventor from Indiana, USA. His puzzles were published in Word Games and Dell Pencil Puzzles magazine in 1979. They were named “Number Place” as there was a need to place different numbers into blank spaces on a 9 × 9 grid.

Sudoku – Adaption of the puzzle in Japan

In 1984, the game appeared for the first time in Japan and was known as “Sudoku.” The name is the short form for the longer Japanese phrase – Sūji wa dokushin ni kagiru. The term Sudoku, meaning one occurrence of every number, has been used since then.

The popularity of the puzzle in Japan is because the native language isn’t quite suitable for crossword puzzles. Therefore, the Japanese culture prefers number puzzles. Moreover, many people in Japan need to make long commutes by bus or train, and the best way to utilize their time is by solving puzzles.

Creating puzzles

The New Zealand judge, Wayne Gould, encountered Sudoku at a bookstore during his vacation to Tokyo in March 1997. He was enthusiastic about the puzzle and invested the next six years developing a computer program that helped produce Sudoku puzzles rapidly.

First Puzzle published

In 2004, the Times of London published Sudoku puzzles. The first U.S newspaper to publish the logic-based puzzle is The Conway Daily Sun. The subsequent years saw Sudoku gaining popularity globally. The first World Sudoku Championship was hosted in 2006 by Italy. 

What is Sudoku – variants of the game

When you ask someone what Sudoku is, the standard response is a 9 × 9 grid puzzle with a few existing numbers and blank cells. However, many other versions of the typical puzzle you see in books and newspapers. These puzzles use different configurations of colors, words, images, and cages, testing your logic much more than the standard 9 × 9 grid.

Here’s a look at six different types of Sudoku puzzles.

  1. Grid Size Variations
  2. Colour
  3. Symbol or Image
  4. Word or Alphabet
  5. Jigsaw
  6. Samurai

Grid Size Variations

The 9 by 9 grid isn’t the only size for a Sudoku puzzle. Other different grid sizes also exist, including the 4 × 4, 6 × 6, 16 × 16, and 25 × 25. The 4 × 4 and 6 × 6 are easier variations, while the 16 × 16 and 25 × 25 variations are a real challenge.


Here, the numbers on a grid are replaced with specific colors. Let’s say blue represents one; red represents two, green represents three, and so on. While the rules to solve the puzzle remain the same, the change is visually engaging and colorful. In the number variant, numbers 1, 2, 3, etc., are used, but with the colors.

Symbol or Image

This version of the puzzle uses images as inputs. The experience is even more interesting since you have to focus on more details instead of numbers or colors. If the images in the puzzle have slight variations, the level of difficulty increases. A smaller grid with apparent differences in images is easier to solve.

Word or Alphabet

When letters replace numbers, it is a word or alphabet variation of the Sudoku. Since letters allow for the creation of words, these puzzles may have hidden words. For instance, apart from completing the 9 × 9 grid with the same logic as other puzzle variations, a 9-letter word needs to be discovered and unraveled. For example, if the letters MRHAYECIN are used to complete the grid, the hidden word is MACHINERY. 


The Jigsaw Sudoku is a little different from the standard Sudoku. In the earlier versions, the cages or nonets are squares with equal blocks. The jigsaw puzzle doesn’t follow these standardizations. It consists of cages in various configurations. The different cage configurations give the puzzle an interesting design that looks like the pieces of a jigsaw puzzle. Since tricks and tips rely on square or rectangle cages, it can be challenging to master and solve jigsaw puzzles.


The Samurai puzzle combines five 9 × 9 grids overlapping each other. It is a challenging puzzle, suitable for those who find the other variations easy. You solve each board as per the regular rules of Sudoku and use the same tricks on the overlapping parts as well. The experience is like playing five different puzzles at the same time.

Sudoku – A Brain game

Sudoku is a simple puzzle with straightforward rules. Many people are passionate about it because of its benefits:

Enhances concentration

Solving the puzzle requires concentration. If there is any interruption or disturbance in logical thinking, it can break the chain of thought. So, playing this game improves focus and concentration as well.

Promotes a healthy mindset

Playing an entertaining and mind-involving game keeps the brain fitter and more active. Consequently, it promotes a more positive mindset.

Helps develop problem-solving skills

Since the puzzle requires the player to engage in logical thinking to solve the grid, it promotes problem-solving skills.

Reduces stress and anxiety

Stress and anxiety have become common mental conditions in our society. The puzzle requires the player to focus on the grid, forgetting about all day-to-day worries. As the brain focuses on the task at hand, there is no time to think about the source of stress and anxiety.

What is Sudoku – Conclusion

Sudoku is an easy-to-learn logic-based number-placement puzzle. It gained widespread popularity in 1986 after Nikoli published it as Sudoku. While the rules to solve the puzzle are quite uncomplicated, the game is infinitely varied. It has millions of possible number combinations and a variety of difficult levels. However, the fundamental principle of filling in the blank cells by logical deductions remains the same.

What is Sudoku? – FAQs

What is the meaning of Sudoku?

The Japanese words suuji wa dokushin ni kagiru are abbreviated to make Sudoku, meaning the numbers must remain single.

What are the basic rules of Sudoku?

The primary rule of sudoku is that each row, column, and 3×3 square grid, in the 9×9 grid must have the digits from 1 to 9 without any duplication. Moreover, every row, column, and 3×3 square must add up to 45 each. Learn how to play sudoku in 6 easy steps.

What is the 45 Sudoku rule?

Each row, column, or nonet in the Sudoku grid contains numbers from one to nine. The rule of 45 suggests that the sum of each of these Sudoku regions is 45. If solved eight blocks in a particular row are solved, and the sum of the digits in the row is S, the number in the remaining block is 45 – S.

Can I find more than one correct answer to the Sudoku puzzle?

No. There is a unique solution for every puzzle. If you are getting multiple solutions, it is a poorly designed puzzle. Many times, the player doesn’t realize that there is a duplicate hidden somewhere on the grid.