KNS Puzzles offers the Light Up puzzles in the following formats:
5 x 5 - Level 1 - Level 2 - Level 3
7 x 7 - Level 1 - Level 2 - Level 3
10 x 10 - Level 1 - Level 2 - Level 3
15 x 15 - Level 1 - Level 2 - Level 3
20 x 20 - Level 1 - Level 2 - Level 3
25 x 25 - Level 1
Light up every square in the grid. A number in a square indicates how many bulbs share an edge (but not diagonally) with that square. A square is lit if it's in the same row or column as a bulb, as long as there are no black blocks between them. No bulb may light another bulb. See the Getting Started section below for extra tips and tricks. What are the numbers for? Each number tells us how many Lights surround that square.
This is the start of the puzzle.
None of these squares can be Lights as they all surround 0 clues.
These are the only three squares that can satisfy the 3 clue.
This is the only square that can light the indicated square. The puzzle is now well on its way to completion.