Light Up Strategy: 6 Techniques
1. Full numbers
If a numbered wall has exactly as many white neighbours as its number, they're all lamps. A 4 in the open, a 3 on an edge, a 2 in a corner.
2. Zeros
A 0 means dots on every neighbour.
3. All but one
A 3 with four white neighbours needs three of them. Then the cell diagonal between any two of those neighbours can't be a lamp (it would see one of them). Dot it.
4. Nothing else can light it
An unlit cell that no other open cell could light must hold a lamp itself.
5. Dots along beams
Once a lamp is placed, every cell it lights gets a dot: no other lamp can be there.
6. Count what's left
Near the end, count the unlit cells in a row: if only one open cell could light them all, it's a lamp.
Frequently asked questions
Where do you start a Light Up puzzle?
With the numbered walls whose count equals the number of white cells beside them (lamps on all of them), and the 0s (dots on all of them).
Last updated 2026-10-20