How to play Light Up
Rules
-
You are given a grid of grey and white squares. The aim is to illuminate every white square by placing light bulbs in the right places.
-
Each bulb emits a horizontal and vertical beam of light, which illuminates the squares in that row and column until it reaches a grey square.
-
Some of the grey squares contain numbers. The number indicates how many of the adjacent cells contain a light bulb (Diagonally touching cells are not included).
-
A bulb may not illuminate another bulb.
Example
To illustrate this, we will walk you through a simple puzzle.
|
We start with a 5x5 grid containing white and grey squares, and three number clues.
The number 3 at the top only has three white squares surrounding it, so these must all contain bulbs.
|
|
The first bulb has been placed. Note that it illuminates itself and all the squares in the same row and column. Bulbs cannot now be placed in the squares that have been illuminated, as this would violate rule 4.
|
|
|
All three bulbs have been placed around the 3. This clue has now been satisfied.
Now look at the zero in the middle. There are two white squares adjacent to it, but the zero means that there can be no bulbs in these squares.
|
|
The white squares around the zero have been marked with a dot, indicating that no bulb can occupy those squares.
This means that there is now only one possibility for the 1 on the right.
|
|
|
All number clues have been satisfied. However, there are still four white squares, and to finish the puzzle we must illuminate them all.
Look at the dotted square to the left of the 1. It cannot contain a bulb itself, so there is only one square from which it can be illuminated.
|
|
The final bulb has been placed, and all squares have been illuminated. The puzzle is now finished.
|
|
Controls
Click on a square to place a bulb.
Click again to mark the square as definitely not containing a bulb.
Click again to empty the square.
You can right click to perform these actions in reverse.
More information
|
