Nurikabe (PuzzleMadness)

Nurikabe is a Japanese shading puzzle. The numbers in the grid are islands, and each island must cover exactly as many squares as its number. Islands may not touch each other side by side, every square outside the islands belongs to one connected body of water, and the water may never form a solid 2x2 block. In a finished grid the islands are white and the water is shaded. On the board a click turns a grey square black for water, a second click marks it white for island, and dragging paints a row of squares in one stroke.

The daily page opens today's puzzle on its own, and its title carries the date (on 3 October 2026 it read "Daily Medium Nurikabe Puzzle for Saturday 3rd October 2026"). There is a separate dated puzzle for each size, and the Mixed page has a grid of its own rather than a copy of one of the others. On 28 October 2026 the Small grid was 7x7, the Medium 8x8, the Large 15x15 and the Mixed 10x10. Past days stay in the archive, so a missed puzzle can be played later, and there is a print version and an image download of the grid. PuzzleMadness does not publish solutions: the site tells you when you have finished a grid correctly or made a mistake. Each completed puzzle adds to your total on the Nurikabe monthly and all-time leaderboards, where only your best score on any one puzzle counts.

Most grids open the same way: surround each 1 with water straight away, and put water on any square that sits between two different numbers, since it would join two islands. After that the 2x2 rule and the need to keep the water connected do most of the work. The small grids are a good place to learn these moves before trying a large one.

PuzzleMadness is a British puzzle site with dozens of daily puzzle types in the browser, from many sudoku variants to logic grids such as Nurikabe, Hashi and Slitherlink. It is free to play and carries ads. A free account keeps track of the puzzles you have finished and puts your name on the leaderboards, and the badges next to usernames mark how many puzzles a player has completed.