Yin-Yang consists of a rectangular or square grid with white and black circles in some cells. The aim is to place a black or white circle in each empty cell so that all circles of same color are connected to each other, vertically or horizontally. Additionally, no 2 x 2 group of cells can contain circles of the same color.
Cross+A can solve puzzles from 3 x 3 to 30 x 30.