Sun and Moon ("Munraito") is a logic puzzle invented by Naoki Inaba (Japan). A square grid contains planets in some cells. The goal is to place exactly one star and one stardust cloud (dark square) into each row and each column of the grid. If a particular semicircle of a planet is illuminated, there must be a star in that rank to light it. A star shines horizontally and vertically only; planets and stardust clouds block starlight.
Cross+A can solve puzzles from 4 x 4 to 20 x 20.