Master of Puzzles - Nurikabe 200 Puzzles 9x9 Vol. 1

Nurikabe is a logic puzzle ("nurikabe" in Japanese folklore is an invisible wall that blocks roads and upon which delays in foot travel are blamed; other names for the puzzle: "Cell Structure," "Islands in the Stream"). The puzzle is played on a grid, typically rectangular with no standard size. Some cells of the grid start containing numbers. The challenge is to paint each cell black or white, subject to the following rules: Each numbered cell must be part of a white island of connected white cells. All of the black cells must be connected. Each island must have the same number of white cells as the number it contains (including the numbered cell). Two islands may not be connected. There cannot be any 2 x 2 blocks of black cells.