Light Up (Akari)

Expert Light Up uses a 12×12 grid with 18% wall density and only 30% numbered walls. The grid is large enough that visibility chains span many cells, and the low density of numbered walls means most deductions come from pure illumination analysis.

Cross-constraint propagation is essential: combining information from multiple walls and corridors simultaneously to force or eliminate cells. A numbered wall near the edge, combined with a corridor constraint from across the grid, may jointly determine a cell that neither alone would resolve.

Mark cells carefully. At this grid size, losing track of eliminations means starting over. Use both hints and the dark-cell toggle to maintain awareness. For the ultimate test, try einstein.