Stained Glass is a binary determination logic puzzle published by Nikoli.
Stained Glass is played on a field of intersecting vertical, horizontal, and diagonal lines. At the intersections of some of these lines are small circles, either unshaded, grey shaded, or completely darkened.
The aim is to shade the correct shapes within the field such that all the circles correctly describe their neighboring areas.
White or black circles bordered by one or two shapes result in all bordering shapes being of the type specified by the circle. Once at least half of the bordering shapes on a grey circle are known to be of one type, the other half should also be known.