How to play Akari

Light up the board by placing bulbs in the correct cells. Every white cell must be lit when you finish.

• Place bulbs on white cells only. Black cells block light and cannot hold bulbs.
• A bulb lights its entire row and column until the light hits a black cell.
• Every white cell must be lit when the puzzle is complete.
• Two bulbs cannot see each other along the same row or column unless a black cell is between them. Conflicting bulbs are highlighted.
• Numbered black cells show how many bulbs must be orthogonally adjacent (touching horizontally or vertically) to that cell.

• In the app, tap a white cell to cycle: empty → bulb → mark → empty.
• Use marks to note cells that cannot contain a bulb.

In the app, tap the Hint button below the board to get help. A hint will suggest either a bulb or a mark on one cell.

• Start with numbered black cells — they constrain where adjacent bulbs must go.
• Use marks to eliminate cells in a row or column once you know where the bulb must be.
• Watch for cells that would create line-of-sight conflicts if they held a bulb.