A quick note before you play
Turn off all 25 lights. Each tap flips one light and its immediate neighbors. Start when you are ready. You can restart at any time, and keyboard controls work after you select the game area. On touch screens, use the on-screen controls or tap the board. No score is uploaded, and there is no account to create.
Think in crosses
A center press changes five lights. An edge press changes four, and a corner changes three. Diagonals do not change. Tapping the same square twice cancels that action, and the order of different presses does not affect the final board.
A way to work through the board
Try working from the top row downward: press directly below a light you want to turn off in the row above. This helps organize your moves, although a final lit row may require revising the first row of presses. Every generated opening comes from legal moves on an all-off board, so a solution exists. The move counter is for your own practice, with no time limit.
Make your own version
This game is also a free template demonstrating grid neighbors, reversible toggles, and solvable puzzle generation. Download its source to explore the logic, change the visuals, and experiment with a new rule.