Tap a tile to flip it and its four neighbours. Turn every light off on a 3×3, 5×5, or 7×7 board. Guaranteed solvable, neon glow, free in browser.
Click or tap a tile. It toggles itself plus the 4 orthogonal neighbours (up, down, left, right). Turn every light off in as few moves as possible. Pick 3×3, 5×5, or 7×7 from the chips.
Lights Out is a deceptively simple electronic puzzle released by Tiger Electronics in 1995. The original handheld used a 5×5 grid of buttons that lit up; pressing one toggled itself plus its four orthogonal neighbours. The goal was to turn every light off — and despite the trivial rules, the math behind it is rich enough to be taught in linear algebra courses today.
Each move you make is an XOR over the affected cells, so the order you press buttons in doesn't matter — only the *parity* of presses does. That property lets a computer solve any 5×5 board in 25 steps or fewer using Gaussian elimination over GF(2), but solving it by feel is much trickier than that makes it sound.
This version offers three sizes — 3×3 for warm-ups, 5×5 for the classic, and 7×7 for serious puzzlers. Every board is generated to be solvable: we start from all-off and "press" random cells, which guarantees the resulting puzzle has a solution. Your best move count per size is saved locally so you can chase a personal record.
On a standard 5×5 board, only about a quarter of all random starting positions are solvable. This game generates puzzles by pressing random cells from an all-off state, which guarantees every puzzle has at least one solution.
It depends on the board. On 5×5 the optimum for most random positions is between 6 and 15 moves. We don't display the theoretical minimum, but your personal best per size is stored locally.
No. Pressing A then B is identical to pressing B then A — and pressing the same cell twice cancels out. Only the *set* of pressed cells matters.
3×3, 5×5 and 7×7 are different puzzles with different theoretical minimums, so each size has its own best record.
Not in this version — Lights Out is small enough that experimenting is part of the fun. If you're stuck on a board, hit "New puzzle" and try a fresh layout.
The electronic puzzle game Lights Out was released in 1995 by Tiger Electronics. Earlier mathematical work by Don Pelletier (1980s) studied the same kind of toggle puzzle on grids.