Logic Puzzle Games: Grid Puzzle Games: MoonSun Puzzles - Best Logic Puzzle Collection (Paperback)

Moonsun ("Moon or Sun") is a logic puzzle invented by Nikoli.
A rectangular or square grid is divided into regions. A grid contains black and white circles in some cells.
The aim is to draw a single non-intersecting loop.
The loop must cross borders of each region exactly twice. In a region, the loop must visit either all cells with black circles or all cells with white circles. Regions with visited black circles must alternate with regions, where white circles were visited.