Turn off every light: Lights Out
Tap a cell to flip it and its four neighbours.
Lights Out is a deceptively tricky logic puzzle. The grid starts with some lights on; tapping any cell flips it and its four neighbours between on and off. The goal sounds easy — switch every light off — but each press ripples across the board, so order and parity are everything.
How to play
Lights Out in 4 steps
Read the board
Some lights start on ✦ and some off. Your goal is to turn every light off.
Tap to toggle
Clicking a cell flips that cell and the four cells directly above, below, left and right of it.
Mind the ripples
Because each tap affects up to five cells, switching one light off often turns several others on. Plan the chain.
Clear the grid
Get every light off to solve the puzzle. Then take a fresh, guaranteed-solvable board.
Controls
- Click / Tap a cell
- Toggle that cell and its four neighbours
- Size buttons
- Choose a 3×3, 4×4 or 5×5 grid
- R
- Generate a new solvable puzzle
Strategy
Tips to play better
Use "chasing lights"
Clear the board top-to-bottom: when a light is on, press the cell directly below it. After the last row, the top row tells you how to finish.
Order doesn't matter
Pressing a cell twice cancels out, so only whether you press each cell an odd or even number of times counts — never the sequence.
Work row by row
Solve the top row first using only the row beneath it, then repeat. This turns a chaotic board into a tidy sweep.
It's linear algebra
Every solvable board has a precise toggle pattern that clears it — the puzzle is really a system of equations in disguise.
About Lights Out
Lights Out was released as a handheld electronic game by Tiger Electronics in 1995, its glowing 5×5 grid making it an instantly recognisable 90s toy. Similar "all-off" toggle puzzles, like the earlier Merlin, had been around for years.
What looks like a casual tap-fest is actually a piece of mathematics. Lights Out is governed by linear algebra over the field of two elements (GF(2)): each solvable board corresponds to a unique combination of "essential" presses, and order never matters because toggling twice returns to the start. This connection makes it a favourite teaching example in discrete maths courses.
Our Unicode version glows with bright ✦ glyphs for lit cells and always generates a board that is guaranteed solvable, so you're never handed an impossible puzzle. Choose a 3×3, 4×4 or classic 5×5 grid, and your best solve — fewest moves — for each size is saved locally in your browser.
FAQ
Lights Out questions
What does tapping a light do?
Is every puzzle solvable?
Does the order of taps matter?
Any trick to solving it?
Is it free to play?
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