Akari solving techniques

Once you know the Akari rules, harder puzzles are mostly about combining two questions: where can a bulb legally sit, and which unlit cells can that bulb reach?

Count remaining neighbours

For each numbered wall, subtract confirmed adjacent bulbs from its clue. Then compare that remainder with the adjacent cells still able to hold bulbs. If the values match, all candidates are bulbs. If the remainder is zero, all remaining candidates are ×.

Use shared neighbours

Nearby clues often compete for the same cells. Suppose a 1 has two possible positions and both also touch a neighbouring 2. The 1 guarantees exactly one bulb among the shared cells, so the 2 must get its other required bulb from outside that shared group. Treat groups of cells as a total instead of guessing which individual cell wins.

Find a cell’s possible light sources

For every unlit cell, scan in four directions until a wall. Exclude positions that see an existing bulb or violate a numbered wall. If only one legal source remains—including the cell itself—that position must contain a bulb.

Watch narrow corridors

A corridor broken into sections by walls may have only a few ways to be lit without bulbs seeing one another. A cell at the far end can force a bulb near that end, which then excludes the rest of its sightline. Recheck perpendicular corridors immediately; one bulb changes both.

Do not confuse lit with impossible

A lit cell can still contain a bulb unless it already sees another bulb or is forbidden by a clue. Conversely, an × cell may remain unlit. Keep “cannot hold a bulb” separate from “already illuminated.”

Sweep after every placement

Each bulb affects its row, column, adjacent numbered walls, and every cell that might have used those sightlines. A quick recount after each forced move is more productive than staring at one clue in isolation.

Practice these deductions in Light the City or try the shared daily Akari. The Akari FAQ answers common rules and progress questions.