Light Up (Akari)

Hard Light Up uses a 10×10 grid with 20% wall density and only 40% of walls numbered. A hundred cells with sparse numbered constraints means you rely heavily on visibility analysis and corridor reasoning.

Multi-cell visibility chains become necessary. A bulb placed in one corridor affects cells in intersecting corridors, which constrains other bulb positions throughout the grid. You need to trace these chains across the board to find forced placements.

Region isolation matters now: groups of cells cut off by walls must be independently solved. Work through one isolated chamber at a time. These puzzles reward patience over speed. For an even bigger challenge, try expert (12×12).