Lights Out
PuzzleHow to Play
Goal: Turn off every light on the board.
Controls: Click or tap a tile. That tile and its four orthogonal neighbors (up, down, left, right) flip between lit and off.
Rules: Every puzzle is generated from an all-off board, so a solution is always guaranteed. Use New Game for a fresh board, Reset Puzzle to restart the current one, and Hint to reveal a tile that belongs to a solution.
About Lights Out
Lights Out is a genuine cult classic: Tiger Electronics released the original handheld in 1995, a 5x5 grid of glowing buttons where pressing any light toggles it and its four neighbors. The task, from a lit starting pattern, extinguish every light, turns out to be one of the most elegant math puzzles ever put in a toy.
Under the hood, Lights Out is linear algebra: the order you press buttons never matters, pressing a button twice is the same as never pressing it, and every solvable 5x5 pattern can be finished in at most a couple dozen presses. There is even a classic technique, light chasing, that solves any solvable board mechanically once you know it.
Lights Out solving technique
- Order never matters, and no button ever needs pressing twice. Think in terms of a set of buttons to press, not a sequence.
- Learn light chasing: sweep row by row, pressing the button directly below each lit cell to push all light into the bottom row.
- Memorize the bottom-row fixes. Each leftover bottom pattern maps to specific top-row presses, then one more chase finishes the board.
- If a board resists, restart your chase from a different top-row press pattern, there are only a few to try.
- Aim to cut your press count, the game tracks your moves, and every solvable classic board has a known minimum.
FAQ
What is the light-chasing method?
Work top to bottom: for every lit cell in a row, press the cell directly beneath it in the next row. This 'chases' all light into the bottom row. Then apply the known top-row press pattern for whatever bottom-row lights remain, chase again, and the board goes dark.
Does the order of my presses matter?
Not at all, toggles commute, so a solution is just a set of cells. This also means pressing any cell twice cancels itself, so if your plan revisits a button you can delete both presses and save two moves.
Is every Lights Out board solvable?
No. On the classic 5x5 grid only one in four random light patterns can be fully switched off; the rest are mathematically impossible. Puzzles generated by pressing random buttons from a dark board, as here, are always solvable.
What counts as a good solution?
Solving at all is the first win; solving near the minimum press count is the real one. Because no cell needs pressing twice, a 5x5 solution never requires more than 25 presses, and most boards fall well under that.
