Who Switched Off the Row: an Akari Investigation
The game was nearly solved. Nine lanterns burned, no dark cells left. I placed the tenth — and the whole middle row went dark.
Examining the scene
Rewind. The tenth lantern landed in the third column. Its beam ran down and crossed the beam of the lantern from row five. Two lanterns saw each other — forbidden. The game flagged the conflict and I removed the newcomer. But the row stayed dark. Why? Because the eighth lantern, the one lighting that row, I had removed five moves earlier as spare. The row had been hanging on side light from the next column, and the tenth lantern blocked it with its shadow. One removed lantern and one extra — that was the whole case.
Questioning the black four
The black cell with a 4 in the corner is the strictest witness. It needs four neighbours, no options. I always start there: place all four at once, then scatter dots along their beams. A dot in Akari is not rubbish, it is testimony: no lantern here, certain. By endgame the dotted field reads like an interrogation file, hiding the very lanterns that hold the rows.
Closing the case
Culprit found: not the tenth lantern, but my belief that the eighth was spare. I put it back, moved the tenth behind a black wall — and everything lit up. Since then I never remove a spare lantern until I check its row is lit from two sides.