Lights rules
How to play Lights
Place lamps on white cells so every white cell is lit. Lamps cannot see each other. Numbered walls need that many lamps on their sides.
Worked example
Use Next to follow each deduction from the starting clues to the finished board.
White cells must end up lit. Lamps never see each other through an open row or column. Numbered walls count lamps on their sides.
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- White cells must end up lit. Lamps never see each other through an open row or column. Numbered walls count lamps on their sides.
- A 0-wall forbids lamps on every touching white cell. Mark those empties first. They never take a lamp.
- The X-marked cell on the top row still needs light. A lamp in the middle would see both remaining lamp places beside the 1-wall, so the lamp must go in the top-right corner. The bottom-left corner follows the same way.
- Each 1-wall already has its corner lamp, so its other white neighbors cannot take lamps. The left-edge X can now be lit only from the cell to its right, and the right-edge X only from the cell to its left. Place lamps in those two cells.
Rules
- Lamps sit on white cells, not on walls.
- Every white cell must be lit.
- A lamp lights its row and column until blocked by a wall.
- Two lamps cannot see each other. A wall between them blocks the view.
- A numbered wall needs that many lamps next to it, up, down, left, or right.
- A wall with no number can have any number of lamps next to it.
Common mistake
A lit cell does not need its own lamp. One lamp can light several cells in its row and column until a wall blocks it.
Controls
Tap a white cell to cycle empty, lamp, and marker. Walls are not tappable. Lit cells show a soft wash from placed lamps.