Fun Logic Puzzles: Kuroshiro Puzzles - Best Logic Puzzle Collection

("Kuroshirorupu"; from Japanese, literally "black and white loop") is played on a grid with black and white circles in some cells. The goal is to draw a single continuous non-intersecting loop that properly passes through all circled cells. Between two successive circles of the same color the loop must not be turned. Between two successive circles of different colors the loop must turn exactly once.