Nonogram is a picture-based logic puzzle that
originated in Japan in the late 1980s. A puzzle in which cells of a grid
must be filled or left blank, according to sets of numbers given at the
side of the grid, to reveal a hidden picture.
A graphics editor called Non Ishida came up with a prize-winning idea to
brighten the night-time cityscape of Tokyo. By switching certain lights
in skyscrapers on or off, he was able to create images on the buildings.