The History of Sudoku
Unlike every other game in this collection, Sudoku has no ancient pedigree at all - it's barely older than the personal computer.
An American Puzzle, First
The number-placement puzzle we now call Sudoku first appeared in 1979 in an American puzzle magazine, published by Dell Magazines under the title 'Number Place'. Its inventor is usually credited as Howard Garns, a retired architect and freelance puzzle constructor, though the magazine never printed bylines at the time, so the attribution rests on circumstantial evidence rather than a signed claim.
The puzzle drew on a much older mathematical idea, the Latin square - a grid where each symbol appears exactly once per row and column - studied by Leonhard Euler in the 18th century, with the added 3x3 box constraint layered on top to make a unique solution reachable by logic alone, without guessing.
A Japanese Name for a Global Craze
The puzzle reached Japan in 1984 through the puzzle company Nikoli, which renamed it 'Suuji wa dokushin ni kagiru' ('the digits must remain single'), soon shortened to Sudoku ('single number'). Nikoli's editors also introduced the now-standard convention of a symmetric pattern of givens and puzzles with only one valid solution.
Sudoku stayed a modest Japanese pastime for two decades until retired judge Wayne Gould, having encountered it on a trip to Tokyo, wrote a computer program to generate puzzles quickly and persuaded The Times of London to start running them in 2004 - triggering a worldwide newspaper puzzle craze within about a year.
From Newspaper Column to Computer Science
Sudoku's sudden popularity attracted mathematicians and computer scientists as much as casual solvers: in 2005, the total number of distinct completed 9x9 grids was computed exactly (a little over 6.6 sextillion), and in 2012 an exhaustive computer search established that no valid 9x9 puzzle needs fewer than 17 givens to have a unique solution.
That second result is exactly the kind of fact PaperGames's generator relies on in reverse: because uniqueness gets harder to preserve as givens are removed, every puzzle here is produced by starting from a full solved grid and removing cells one at a time for as long as a unique solution survives - the same logic, worked backward, that puzzle constructors have used since Nikoli's earliest issues.