How to play
Tap a tile to toggle it and the tiles beside it. Turn all lights off in as few moves as you can.
About Lights Out 5x5
Lights Out 5x5 looks harmless. Twenty-five square tiles, some lit up yellow, some dark. All you have to do is switch every light off. The catch is that pressing a tile flips not only that tile but also the ones directly above, below, left and right of it. Fix one corner and you break another. It is a small puzzle with a surprising amount of depth.
The rules
Tap any tile. That tile changes state, from on to off or from off to on, and so do its neighbours on the four sides. Diagonals are not affected. Tiles on an edge have three neighbours and corner tiles have two, so they flip fewer lights. The puzzle is solved when the whole board is dark, and the move counter at the top tells you how many presses it took. Tap once more for a new board.
Every puzzle here can be solved. The game builds each one by starting from a dark board and pressing a dozen tiles at random, so there is always a way back.
Two facts that make it easier
First, pressing the same tile twice does nothing. The second press undoes the first. So there is never a reason to press any tile more than once in a solution, and if you catch yourself doing it, you have wasted two moves.
Second, the order of your presses does not matter. Pressing tile A and then tile B leaves the board exactly as it would be after B and then A. The puzzle is really a question of which tiles to press, not when.
A method called chasing the lights
If you would like a reliable way through, try this. Look at the top row. For every light that is on, press the tile directly underneath it, in the second row. That switches off the whole top row. Now do the same for the second row by pressing tiles in the third, and keep going down the board.
When you reach the bottom, the first four rows will be dark and only the last row may have lights left. From here, people who study the puzzle use a short set of patterns that tell them which top-row tiles to press before chasing down again. You do not need to memorise them to enjoy the game. A bit of trial and error on the top row, followed by another chase, will get you there, and you will start to recognise the patterns on your own.
Playing for a low move count
Finishing is one challenge. Finishing efficiently is another. Because each board is made from at most twelve presses, a solution of twelve moves or fewer always exists. If your counter reads thirty, the puzzle got solved the long way round. Try to spot small shapes you can clear in one press, such as a plus sign of five lights, which a single tap in its centre wipes out.
Who will enjoy it
Lights Out is for people who like to sit and think. There is no clock and no penalty for a wrong move, so you can experiment freely. It suits a quiet break, and it is a good one for older children who enjoy logic puzzles.
The game runs in your browser on any phone, tablet or computer, free and without a download.