Fobidoshi ("Forbidden Four") is a logic puzzle, invented by Naoki Inaba (Japan). It is played on a rectangular or square grid. Some of the cells have circles in them. The aim is to place circles into empty cells; all the circles must form an orthogonally continuous area. A line of connected circles must not contain more than 3 circles.
Cross+A can solve puzzles from 4 x 4 to 30 x 30.