Moves 0
Lights on 0
How to play
Goal
Switch off every light on the grid.
How it works
- Tap a square to flip it and its four neighbours (above, below, left and right). Lit squares go dark and dark squares light up.
- Squares on the edge have fewer neighbours, so they flip fewer lights.
- Every puzzle can be solved. Choose 3×3 to learn the idea, 5×5 for the classic game.
Tips
- The order of taps does not matter, and tapping a square twice undoes it. So a solution never needs the same square twice.
- Try “chasing the lights”: work down row by row, and for each light still on, tap the square directly below it. That clears every row except the last.
- The pattern left in the bottom row tells you which squares in the top row to tap before chasing again. Experiment to learn the patterns.
The history of Lights Off
This puzzle became famous as a handheld game from Tiger Electronics in 1995. The idea is older: a 1983 game called XL-25 used the same rules, and mathematicians have studied the puzzle using linear algebra.