Sudoku seems to have been around forever, well certainly since the mid 1980’s when its popularity became much more widespread. But the roots of the puzzle stretch back way further to the 18th century, where mathematicians developed “Latin squares”. The first modern form of Sudoku puzzle appeared in 1979 by an American puzzle creator Howard Garns under the name “Number Place”. Later in 1986 the Japanese puzzle company Nikoli coined the name Sudoku (meaning “single number”) and the name has stuck ever since.
The classic 9x9 Sudoku has 6,670,903,752,021,072,936,960 possible unique puzzle grids. A book containing all of those puzzles would be roughly 37 light years thick, reaching from Earth way beyond most of the stars we can see. Or if those puzzles were divided into roughly 7 billion individual books of a trillion pages each, the entire Earth population working simultaneously would take at least a million years to solve them all.
The widespread appeal lies in the puzzle’s ability to engage the brain without requiring mathematical expertise, thus making it accessible to a broad audience. It's thought that regular Sudoku completion offers significant mental health benefits. It can enhance cognitive function through improving memory, concentration and problem solving skills.
Sudoku can be a fun challenge at all levels and suitable for a wide range of ages from young children to senior adults. The focussed attention required for solving puzzles can also be quite therapeutic, almost as a meditative activity by reducing stress and anxiety. That may not be true for some of the more extreme puzzles!