nikoli.com
Puzzle site run by Nikoli - Slitherlink, Nurikabe, Heyawake, Akari, Hitori, Masyu, Shikaku, Numberlink, Kakuro and Sudoku
Puzzle site run by Nikoli - Slitherlink, Nurikabe, Heyawake, Akari, Hitori, Masyu, Shikaku, Numberlink, Kakuro and Sudoku