How to play
- Select a tile to switch that light and its horizontal and vertical neighbors.
- Watch which positions change and plan moves rather than tapping randomly.
- Turn on the full 3 × 3 board, then compare your move count with the reference target.
What this game practices
Strong for discussing reversible moves and planning from an observed rule. It is deliberately small enough to reason about, though it does not assess formal proof or generalize automatically to larger Lights Out boards.
How we checked it
Original coolmath puzzle. Included boards are generated from valid move sequences so every presented state has a known solution path.
Reviewed by coolmath Editorial Team · Updated 2026-09-20