Place bulbs to illuminate every cell, without any two lighting each other, and satisfy the wall clues.
Place light bulbs on the white cells. Each bulb shines along its row and column until a black wall blocks it. Every white cell must end up lit, no bulb may shine directly on another bulb, and every numbered wall must touch exactly that many bulbs in the four cells around it.
Published by Nikoli, this puzzle carries two Japanese names that describe it from opposite ends: 美術館, bijutsukan, "art gallery", for the room being lit, and 明かり, akari, "light", for the thing doing the lighting.
It is a binary-determination puzzle — every white cell either holds a bulb or does not, and nothing in between. A bulb illuminates its whole row and column until a black cell blocks it, numbered black cells state exactly how many bulbs touch them, and no bulb may shine on another.
That last rule is what makes it a logic puzzle rather than a covering problem. Bulbs both solve and constrain: each one lights a region and simultaneously forbids every other cell in its line, so the grid is as much about where a bulb cannot go as where one must.
Light Up is an original build of the bulb-placement logic puzzle, free to play in your browser with a daily board and endless practice. Made in-house at PlayPendium.