Hardest Puzzles: Mochikoro Puzzles - 200 Hardest Puzzles With Answers (Paperback) (ISBN-13: 9781981014620)

Mochikoro ("Mochinuri") is a logic puzzle. It consists of a grid, with numbers in some cells. The aim is to blacken some cells according to the following rules: -The black cells divide the grid in rectangular areas ("islands") of white cells. -No two islands may share an edge, but all of the islands must be connected to each other through their corners. -Each numbered cell must be a part of a white island. Some white areas may not include a cell with a number. -Each island must have the same number of white cells as the number it contains (including the numbered cell). -No 2 x 2 cell area within the grid can contain all black cells.