Sukima (from Japanese "Sukimaburokku"; literally "space between blocks") is a logic puzzle created by Naoki Inaba (Japan). A rectangular or square grid contains circles in some cells. The aim is to locate some regions in the grid, having the size of exactly three cells. Each region contains one circle. Each 2 x 2 area must contain at least one cell, that does not belong to any region. Black cells do not belong to any region.
Cross+A can solve puzzles from 3 x 3 to 30 x 30.