Pressing a light switches it and the lights next to it. Turn the whole board dark, level after level, on 5×5, 6×6 or 7×7 boards.
What is Lights Off?
Lights Off is a lights out puzzle: a square grid of lights in which pressing any light switches it and its neighbours above, below, left and right, and your goal is to turn every light off. A light that is on goes off, a light that is off comes on, so each press changes up to five lights at once.
The puzzle looks like trial and error at first, but it is fully logical. Two simple facts about presses make it possible to solve any board step by step, and to aim for the fewest presses, which is what the game measures.
How to play Lights Off
Pressing: tap a light to press it. It flips, together with the lights directly above, below, left and right of it. A light on the edge has three neighbours and a corner light has two, so presses there change fewer lights.
Goal: turn off every light on the board to solve the level. The Moves counter shows how many presses you have made, and the Fewest counter shows the smallest number of presses that solves this level from its starting position. Matching Fewest gives the full score.
Levels: solving a level unlocks the next one. Each board size has its own run of levels, and the arrows beside the level number take you back to levels you have already opened. Restart puts the current level back to its start.
Boards: you can play on 5 by 5, 6 by 6 or 7 by 7. Every level can be solved, because each one is made by pressing lights on a dark board, and the same level number on the same size always shows the same pattern.
How to solve Lights Off
Two rules to remember. First, the order of presses does not matter: pressing A then B gives the same board as B then A. Second, pressing the same light twice cancels out. So a solution is a set of lights, each pressed once, and any light pressed twice is two wasted moves.
Look for crosses on early levels. A single press on a dark board makes a plus shape of five lights, or a T on an edge, or a small corner of three. The first levels are made with only a few presses, so the board is often a few of these shapes laid over each other. Press the centre of each plus and the board goes dark.
Chase the lights down. For any board, work from the top row down: for every light still on in a row, press the light directly below it. This turns off each row in turn and pushes all remaining lights into the bottom row.
Fix the bottom row on 5 by 5. Once only the bottom row is lit, press certain lights in the top row and chase down again; the board will end dark. Read the lit lights in the bottom row from the left, numbered 1 to 5. If 1, 2, 3 are on, press top light 2. If 1, 2, 4, 5: press 3. If 1, 3, 4: press 5. If 1 and 5: press 1 and 2. If 2, 3, 5: press 1. If 2 and 4: press 1 and 4. If 3, 4, 5: press 4.
Matching Fewest. On 6 by 6 and 7 by 7, every board has only one set of lights that solves it. That means if you solve a level without ever pressing the same light twice, you have matched Fewest. On 5 by 5, every board has four different solving sets, so the chase method may solve it with more presses than needed. The Hint button points to a press from the shortest solution, so you can use it to learn what the shortest set looks like.
Board sizes and other versions of the puzzle
Our Lights Off offers three board sizes: 5 by 5, the size of the original handheld game, 6 by 6 and 7 by 7. Levels start with a board made by three presses and add one press every two levels, up to half the number of lights on the board, so later levels need longer solutions.
Other versions of the puzzle exist: some use lights with more than two states, some flip the diagonal neighbours as well, and some are played on larger or non-square boards. On a 5 by 5 board in general, only a quarter of all possible light patterns can be solved at all. Our levels never run into that, since each one starts from a dark board.
Where the lights out puzzle comes from
The puzzle became widely known through Lights Out, an electronic handheld game released by Tiger Electronics in 1995 with a 5 by 5 grid of lit buttons. Our game uses the name Lights Off and is not connected to that product.
Mathematicians have studied the puzzle as a problem in linear algebra, where each light is either on or off and every press adds a fixed pattern. That approach explains which boards can be solved, why the order of presses does not matter, and how many solutions each board has. The game itself uses the same method to compute Fewest and the hint.
Play Lights Off on Hevagames
Our Lights Off runs in the browser on phones, tablets and computers, with nothing to download. Tap or click a light to press it. On a keyboard, the arrow keys move between lights, Enter or Space presses, H highlights one light to press and R restarts the level. Hints have no limit and do not cost points.
Each solved level gives 100 points, minus 10 for every press above Fewest, with at least 20 points per level. Points add up across levels into your total. Your progress on each board size, the level in progress and your best score are saved in your browser.
How to play
- 1Press a light to switch it and its neighbours above, below, left and right.
- 2Turn every light off to solve the level.
- 3Fewest shows the smallest number of presses that solves the level. Try to match it.
- 4Solving a level unlocks the next one. Use the arrows beside the level number to go back to earlier levels.
Controls
Tips
- Pressing a light twice cancels out, and the order of presses does not matter.
- Work row by row: for each light still on, press the light directly below it. Then only the bottom row is left to sort out.
- Hint always points to a press from the shortest solution for the board as it is now.