Truyền thống Nikoli

Sources & notes

1. “Nikoli (publisher),” Wikipedia: a Japanese publisher specialising in games and, especially, logic puzzles. Nikoli is also the nickname of a quarterly magazine, Puzzle Communication Nikoli, issued by the company in Tokyo; the company was established in 1980 and takes its name from the racehorse that won the Irish 2,000 Guineas that year. It became prominent worldwide with the popularity of Sudoku, whose Nikoli form was popularised in the English-speaking world in 2005. Nikoli is notable for a vast library of culture-independent puzzles: unlike a language-dependent genre such as the crossword, which relies on a specific language and alphabet, its puzzles turn on logic alone, and a reader in any language can attempt them. The magazine has invented several new genres of puzzle and introduced several new games to Japan, and the article’s list of Nikoli puzzles runs to dozens of types, among them Sudoku, Kakuro, Slitherlink, Nurikabe, Masyu, and Hitori. en.wikipedia.org/wiki/Nikoli_(publisher).
2. “Maki Kaji,” Wikipedia: Kaji (1951–2021), later president of the puzzle publisher Nikoli, launched a quarterly puzzle magazine called Nikoli in 1980 together with two friends from his childhood, naming it after a racehorse that had won the 1980 2000 Guineas Stakes in Ireland; he founded a company of the same name three years later. Sudoku appeared in early issues, and he formulated its name by shortening a longer Japanese phrase. He is widely known as the father of Sudoku for his role in popularising the game. en.wikipedia.org/wiki/Maki_Kaji.
3. Star Battle game engine: a pure, deterministic implementation of the puzzle, with no browser code in it. The board is an N by N grid divided into N contiguous regions; the regions are grown by a seeded random walk, so they are irregular and uneven in size, and each holds exactly K of the stars. The player places exactly K stars in every row, every column, and every region, with no two stars touching, not even diagonally, adjacency being tested over every neighbouring cell including the diagonals. Three difficulties set the size and the star count: easy is 6 by 6 with one star per line, medium 8 by 8 with one, and hard 10 by 10 with two. A cell is empty, holds a star, or holds an X elimination note, and clicking cycles it through those three states. Generation is deterministic from the seed and difficulty: the engine lays a valid star solution, grows the regions around it, then reshapes region boundaries until a backtracking solver, counting solutions only as far as two, confirms that exactly one remains; the same solver drives the hint. Further checks test a finished board, flag stars that touch, and flag rows, columns or regions holding more stars than the rules allow. Read from the game’s own source.
4. “Sudoku,” Wikipedia: the modern puzzle was most likely designed anonymously by Howard Garns, a retired architect from Connersville, Indiana, and first published in 1979 by Dell Magazines as Number Place. It was introduced in Japan by Maki Kaji, president of the Nikoli puzzle company, in April 1984 under a title later abbreviated to Sudoku. en.wikipedia.org/wiki/Sudoku#History.