Lantern Rooms
A lighting puzzle. Each lamp shines along its row and column until a wall stops it. Light every white cell, keep lamps out of each other's light, and give each numbered wall exactly that many neighbouring lamps.
Place lamps so every white cell is lit, no lamp shines on another, and numbered walls get exactly that many lamps.
FreeOn this device
Solved on this device: 0 of 12. Every board has exactly one answer, checked by a solver.
Controls
- Tap a white cell to cycle lamp, no-lamp mark and empty.
- With the keyboard, move with the arrow keys; L places a lamp, X marks no-lamp, Backspace clears, Space or Enter cycles.
- Check lists broken rules, Hint explains one step and Apply hint carries it out; Undo and Reset are always available.
The rules
- A lamp lights its own cell and every white cell in its row and column up to the nearest wall or edge.
- No lamp may be lit by another lamp.
- A numbered wall has exactly that many lamps directly above, below, left or right of it. Plain walls have no rule.
Scoring, saving and limits
Solved means every white cell is lit and both rules hold — lighting everything is not enough on its own. A hint that reveals a lamp marks the run as assisted.
Your lamps, marks, undo history and solved boards are kept on this device only. Download a backup to move them.
Twelve original boards (six 5×5, six 7×7), each checked by a solver to have exactly one answer within the in-page search budget. Hints look for a forced wall neighbour or the only remaining light for a corridor; otherwise they reveal a lamp and say so.
Questions
- Do lamps shine diagonally?
- No — only straight along the row and column, and walls block them.
- What do the no-lamp marks do?
- Nothing to the rules. They are notes for cells you have ruled out.
- Why is my fully lit board not solved?
- Check for two lamps lighting each other or a numbered wall with the wrong count — the Check button names which.