About Lights Out
Lights Out is a grid of lights and one rule: pressing a cell flips it and its four neighbours. Turn them all off. It sounds like a game about trial and error, and for about ten minutes it is, until you notice the two things that make it a real puzzle. Order does not matter, and pressing the same cell twice is the same as not pressing it at all.
Those two facts mean a solution is not a sequence but a set — you are choosing which cells to press, not when. That turns the whole thing into linear algebra over two elements, which is why this version can tell you the minimum number of presses for the board in front of you. Every puzzle here is generated so it is solvable, and the target is the real optimum, computed rather than estimated.
How to play
- Click any cell to toggle it and its four orthogonal neighbours. At the edges the shape is simply clipped.
- The goal is to turn every light off.
- The optimal count shown is the smallest number of presses that solves the board you were dealt.
- Pressing the same cell twice undoes it, so a wrong press costs you two moves, not a lost puzzle.
- Arrow keys move the focus ring and Enter or Space presses, if you would rather not use the mouse.
Five tips that actually move your score
- Learn the chase. Work top to bottom: for every lit cell in a row, press the cell directly beneath it. That clears every row except the last one, every time, and it is the backbone of every solution.
- The last row is the whole puzzle. After the chase, whatever is left lit on the bottom row tells you exactly which cells in the top row you should have pressed. There are only a handful of patterns; learning them turns the game from guessing into looking up.
- Order never matters. You can press the same set of cells in any sequence and get the same board. If you are trying to remember what you did, remember which cells, not the order.
- Two presses cancel. Undoing a mistake is just pressing the same cell again. Nothing is ever ruined, only lengthened.
- Chase the optimum, not the clear. Solving a 5×5 in twenty presses is easy. Solving it in the seven the counter is showing you is the actual game.
Frequently asked questions
Is every puzzle solvable?
Yes. Boards are built by applying random presses to an already-solved grid, which guarantees a solution exists by construction.
How is the optimal move count calculated?
By solving the board properly rather than guessing: the game tries every possible first-row pattern, propagates each one downward — every later row is forced by the one above it — keeps the patterns that finish with a dark board, and takes the smallest.
Why do hints not count for a personal best?
Because the record is the number of presses you worked out yourself. A hinted run still finishes and still shows your time; it just is not filed as a best.
Do the different board sizes share a record?
No. 4×4, 5×5 and 6×6 each keep their own best, since they are effectively different puzzles.
