Wamuzu ("Worms") is a logic puzzle invented by Naoki Inaba (Japan). It consists of a grid, with circles in some cells. The goal is to connect circles in pairs by drawing a line that goes horizontally and vertically through the centers of cells. All cells must be used by the lines. All sections of each line must be equal to the length of the cell's side.
Cross+A can solve puzzles from 3 x 3 to 30 x 30.