Nine-cell lights out
Press a cell to flip it and its orthogonal neighbours. Turn all nine lights off.
How to use
Solve five fixed 3×3 lights-out puzzles together. A cell flips itself and its orthogonal neighbours; turn all nine off. Boards stay visible with no timer. Undo one move or confirm a reset, then see each puzzle’s move count when finished.
Start in three steps
- Read the rules and begin the five-puzzle challenge. Cells are numbered 1–9 from left to right, top to bottom, and each shows On or Off. Discuss together and have one person operate.
- Each press flips the cell and its existing up, down, left and right neighbours and adds one move. No diagonals or wrapping. Before solving, undo the latest move or confirm a reset of this puzzle.
- Once all nine lights are off, the board locks. Select Next puzzle manually; after puzzle five, select View completion to see 5/5 and all five move counts. Restarting requires confirmation. There is no minimum-move target or ranking.
Storage and limitations
Boards, moves, one undo snapshot and results stay in the current page memory, never in the URL, persistent storage or a server. Refreshing or leaving clears them. Other controls lock during reset or restart confirmation; cancelling keeps the entire state. There are no random puzzles, hints, automatic solutions, timers or multiplayer connections.
Frequently asked questions
How do undo and reset differ?
Undo restores the board and move count before the latest valid cell press, then clears the snapshot. There is no redo. Reset requires confirmation before restoring this puzzle’s fixed initial board and zero moves; cancelling keeps everything. Both work only before solving.
Does solving advance automatically?
No. All nine cells, undo and reset lock when the lights are off. Select Next puzzle after the first four or View completion after the fifth. Results list the actual move counts, with no minimum required and no sixth puzzle.
Can I resume lights out after refreshing?
No. All game data stays in page memory and is cleared by refreshing or leaving. Restarting after completion asks for confirmation. Cancel keeps all five results; confirm returns to the start before puzzle one.