Lights Out
Moves: 0Best: -
- Category
- Puzzle
- Players
- 1
- Controls
- Tap
- Grid
- 5 x 5
- Loads
- Instant
Controls
| Tap a square | Flip it and its four neighbours. |
| New puzzle | Generate a fresh board. |
Next up
| Tap a square | Flip it and its four neighbours. |
| New puzzle | Generate a fresh board. |
Lights Out gives you a grid of lights and one rule: pressing a square flips it and its four neighbours. Turn every light off. It sounds simple and it defeats almost everyone on their first attempt, because every move you make undoes part of the last one.
The puzzle was a handheld toy in the mid-nineties and became a favourite of mathematicians, because it turns out to be a system of linear equations in disguise. Solving it properly is not about clicking cleverly but about realising that the order of your presses does not matter at all, only which squares you press and how many times.
Order does not matter, only parity. Pressing the same square twice returns the grid to where it started, so a solution is just a set of squares each pressed once. That single insight changes how the puzzle feels entirely.
Work top row down, a technique called chasing the lights. Whenever a light is on, press the square directly beneath it. That clears each row in turn and pushes every remaining problem to the bottom row.
The bottom row tells you the answer. After chasing, whatever pattern is left along the bottom determines which squares in the top row you should have pressed to begin with. Experienced solvers learn a handful of these bottom patterns by heart.
Do not click randomly when stuck. Random presses scramble the parity you have built up, and it is almost always faster to start again and chase properly than to poke at a half-solved board.
It flips that square and the four squares directly above, below, left and right of it.
Yes. Boards are generated by scrambling a solved grid, so a solution always exists.
No. Only which squares you press, and whether you press each an odd or even number of times.
The standard technique: work down the grid pressing beneath any lit square, which reduces the puzzle to a known bottom row pattern.
No sign-up, no email, no account. Open the page and Lights Out is ready to play straight away, on a phone or a desktop.