One move, up to five changes.
Choose any tile, whether it is on or off. That tile and its immediate neighbours above, below, left and right all flip. On becomes off; off becomes on.
- A centre tile flips five tiles: itself and four neighbours.
- An edge tile flips four tiles.
- A corner tile flips three tiles.
Diagonals never change. The pattern stops at the edge of the board; it never wraps around to the other side.
You win when every tile is dark. There is no timer or target score. Take your time to find a solution.
Start small. Look for the ripple.
Try a 3 × 3 board first. Before tapping, picture the cross that will change. A move can switch some lights off while switching others on, so fewer glowing tiles does not always mean you are closer to a solution.
Two useful things to notice:
- Pressing the same tile twice cancels out. If a move surprises you, tap it again or use Undo.
- The order of a set of moves does not change the final board. Think about which tiles to press, rather than finding a perfect sequence.
A dark tile may be exactly the tile you need to press. You can experiment freely: every board starts from a solvable pattern, and every legal move keeps it solvable.
A daily ritual, or another round.
Daily gives everyone the same board for the same size and UTC date. There are separate 3 × 3, 4 × 4 and 5 × 5 boards. The date changes at 00:00 UTC, which may be a different time in your location.
If a new day begins while you are playing, you can finish the board already open or choose “Play today’s board.” Your saved daily board stays available when you reopen. Choose Play today to replace it; an unfinished board asks for confirmation.
Practice gives you fresh puzzles whenever you want. Choose “New practice puzzle” to replace the current practice board. Switching between sizes or modes keeps each board’s progress on this browser when storage is available.
A little help, when you want it.
Undo takes back your last move, even after you finish. Restart restores the same starting board and clears that attempt’s moves and hints.
Hint outlines one tile that belongs to a valid solution from your current board. Tap the outlined tile, then ask again if you need another step. It is a way forward, not a promise of the fewest possible moves.
Moves counts the moves in your current attempt. Undo subtracts the move it reverses. A completed board also tells you whether you used hints.
Tap, click, or use the keyboard.
On a phone, tap a tile. With a keyboard, use Tab to enter the board, then the Arrow keys to choose a tile. Press Space or Enter to flip it. Press Tab again to reach the game controls.
Each tile announces its row, column and on/off state to assistive technology. Hints include the suggested row and column.
Your next visit.
The game saves progress in this browser on this device. No account is needed. Private browsing, clearing site data or blocking browser storage may remove or prevent those saves.
If a saved game cannot be read, you can keep playing without saving. The game will ask before replacing that record. Read the privacy information.