Play Now
Light Up (Akari)
Light Up, known in Japan as Akari, is a logic puzzle from Nikoli. You place light bulbs on a grid of white and black cells so the whole board is illuminated. Each bulb sends light along its row and column until a black wall stops it.
Light Up (Akari) Rules
You place bulbs in white cells. A bulb lights its own cell and shines outward in all four directions along the row and column, until the beam is blocked by a black cell or the grid edge.
Every white cell must end up lit by at least one bulb, and no bulb may shine directly onto another bulb — two bulbs cannot share an unobstructed row or column line.
Some black cells carry a number from 0 to 4, stating exactly how many bulbs must sit in the white cells orthogonally adjacent to it. When the whole grid is lit, no bulbs see each other, and every numbered wall is satisfied, the unique solution is reached.
Light Up (Akari) Strategy & Tips
Resolve numbered walls first
A wall labeled 4 forces bulbs in all four neighbors; a 0 forbids them entirely. These give certain placements and certain empties to start the chain of deductions.
Find cells only one bulb can reach
A white cell with walls hemming it in may be lightable from just one position. If only a single cell can illuminate it, a bulb must go there.
Block conflicting lines
Once a bulb is placed, every other cell in its unobstructed row and column cannot hold a bulb. Mark those as bulb-free to narrow remaining options.
Use partial wall counts
If a numbered wall already has its quota of bulbs, its other neighbors must stay empty. Conversely, if its remaining empty neighbors equal its remaining count, fill them all.
Frequently Asked Questions
How does Light Up (Akari) work?
You place light bulbs so every white cell is illuminated. Bulbs light their row and column until blocked by a black cell, and no bulb may illuminate another bulb.
What do the numbers on black cells mean in Akari?
A number tells you exactly how many bulbs must be placed in the white cells directly above, below, left, and right of that black cell.
Can two bulbs light each other in Akari?
No. Two bulbs may not share an unobstructed row or column. If nothing blocks the line between them, the placement is illegal.
What is the goal of Light Up?
To illuminate every white cell on the grid while satisfying all numbered walls and ensuring no bulb shines directly on another.