How to Play Light Up
Light Up is a logic puzzle about lighting a grid of rooms.
The rules
- Put lamps on white cells. A lamp lights its whole row and column, in all four directions, up to the nearest black wall.
- Every white cell must be lit.
- No lamp may light another lamp (two lamps can't see each other along a row or column).
- A number on a wall says how many lamps are directly next to it: above, below, left or right. A wall with no number can have any number of lamps beside it.
First deductions
- A wall marked 0 has no lamp beside it: dot those cells.
- A wall marked 4 (or 3 on an edge, 2 in a corner) has a lamp on every side.
- A white cell that nothing else can light must be a lamp.
On kawu
- Tap a cell for a lamp; tap again for a dot ("no lamp here"); tap again to clear. Keys: L, D, Backspace.
- Lit cells turn yellow. Lamps that see each other are outlined in red; walls with too many lamps show red numbers.
- Every puzzle has one solution and can be solved by logic. The daily puzzle is 10×10.
Frequently asked questions
Can a lamp light through a wall?
No. A lamp lights along its row and column until the first black cell in each direction.
Do lamps count diagonally for a numbered wall?
No. Only the cells directly above, below, left and right of the wall count.
Last updated 2026-10-20