Furisuri ("Free Three") is a logic puzzle invented by Naoki Inaba (Japan). A rectangular or square grid contains circles in some cells. The goal is to locate some blocks in the grid, having the size of exactly three cells. Each block must contain one circle. It must be possible to move each block by one cell in at least one direction.
Cross+A can solve puzzles from 3 x 3 to 30 x 30.