Lights Out: how to play and solve the puzzle

How to play

1. Some rune lamps start lit. The goal is a dark board: every lamp off.
2. Pressing a lamp flips it and the lamps directly above, below, left and right of it. Lit lamps go dark and dark lamps light up. Lamps on the edge have fewer neighbors.
3. Pressing the same lamp twice puts everything back, and the order of presses never changes the result, so a solution is just a set of lamps to press once each.
4. Each press counts. Par is the fewest presses that clear the board; the timer starts with your first press and pauses when you choose Pause or leave the tab.
5. Every board is made by pressing random lamps on a dark board, so it can always be switched off.
6. Hint rings one lamp from the shortest way out. Restart brings back the starting lamps; New puzzle deals a fresh board.

Controls

Mouse

Click a lamp to press it.

Touch

Tap a lamp to press it. Each lamp is a large target, even on the 7×7 board.

Keyboard

Arrow keys or WASD move between lamps; Space or Enter presses the focused lamp. Tab reaches the size picker, Hint and Restart.

Score and progress

The press counter adds one for every lamp you press. The timer has no limit and stops when the board goes dark. Fewest presses and fastest time are saved separately for each board size in this browser when local storage is available; boards solved with a hint count as solved but do not set a best.

Tips

• Corners touch only three lamps and edges four, so a lit corner is often cleared from the cell next to it.
• On 3×3, pressing the centre flips a plus shape; pressing a corner flips an L. Learn those two shapes and small boards solve themselves.
• Never press the same lamp twice: it only undoes the first press and costs two moves.
• If a chase leaves the bottom row lit in a pattern you do not recognise, press Hint once and watch which top-row lamp it picks.

Stuck? The game opens your current board in the Lights Out Solver, which shows the fewest presses from there and replays them one at a time.

How to solve Lights Out by hand: chase the lights

You do not need to see the whole answer at once. Push the lights down to the bottom row, then use what is left to fix the top row.

1. Chase down. For every lit lamp in the top row, press the lamp directly below it. The top row is now dark. Repeat for the second row, pressing under each of its lit lamps, and so on to the bottom.
2. Read the bottom row. After a full chase only the bottom row can still be lit. On a 5×5 board there are only seven patterns it can show.
3. Fix the top row. Each bottom pattern matches a set of top-row presses. On 5×5: if the bottom reads lit-off-off-off-lit (first and last), press the 1st and 2nd lamps of the top row; if it reads off-lit-off-lit-off, press the 1st and 4th; if it reads lit-lit-lit-off-off, press the 2nd.
4. Chase again. After the top-row presses, chase the lights down once more. The board ends dark.
5. Tidy up for par. A chase solution is rarely the shortest one. Any lamp you pressed twice cancels out, and on 4×4 and 5×5 some boards have several solutions; par counts the shortest.

Why some Lights Out puzzles cannot be solved

Every press is its own undo, and presses commute, so solving Lights Out is a system of equations over the numbers 0 and 1: one equation per lamp, one unknown per press. On some sizes the presses are not independent. On 5×5, three different sets of presses (besides pressing nothing) leave the board unchanged, which means only one light pattern in four can be switched off; on 4×4 it is one in sixteen. On 3×3, 6×6 and 7×7 every pattern has exactly one solution. Boards in this game come from random presses on a dark board, so they are always among the solvable ones.