Nurikabe

Also known as:

Islands in the Stream

A Nurikabe is an invisible wall in Japanese folklore that impedes or misdirects walking travellers in the night. The puzzle Nurikabe, was devised by one of Nikoli's puzzle compilers in the early 1990s. Nikoli admits the rules are more complex than some other puzzles, but insist that this has not impeded its popularity and it is still a very popular puzzle in Japan today.

The other name of the puzzle, Islands in the Stream, beautifully conveys the objective of the puzzle.

The rules of the puzzle are the keys to solving and beginners should always bear in mind that the wall, or stream, cannot contain a 2x2 square; and that the wall or stream is a single, contiguous object. It is usually easy to make a start. Cells that are orthogonally adjacent to a 1 can be shaded. If a cell lies directly between digits it can be shaded, too, as it is not permitted for islands to touch, orthogonally. Next, look at the corners and tight parts of the grid. The final parts often tumble easily, leaving the solver with a warm feeling and the urge to tackle another puzzle.

Instructions


Shade in cells to create islands of white cells, surrounded by a contiguous black wall.

The rules are as follows:

• Each white area contains only one number, which cannot be shaded in, and which denotes the number of cells within that island.

• All white areas must be separated by a black wall (horizontally and vertically).

• The black cells must all link up into a continuous wall. The wall cannot contain a 2x2 square.

Related Puzzles

Bridges Loop-The-Loop Masyu Sudoku