Dotchi-Loop is a logic puzzle published by Nikoli. A rectangular or square grid is divided into regions. A grid contains white and black circles in some cells. The goal is to draw a single non-intersecting loop. The loop must visit all cells with white circles; the loop cannot pass through a black circle. The line either travels straight through all the white circles, or makes a 90 degrees turn at all the white circles in a region.
Cross+A can solve puzzles from