Home / Puzzle / Light Bulb Grid
Light Bulb Grid is a free online lights-out puzzle: a panel of bulbs where pressing any one of them flips that bulb and the four bulbs directly above, below, left and right of it. Your job is to switch the whole panel off. It sounds simple and it is not — every press undoes part of what the last one did, and the order you press in makes no difference at all, so the puzzle is really about which set of bulbs to press. That property is what lets this version score you honestly: it solves each board mathematically and shows you the shortest possible solution, so "Best 6" really means six presses is the minimum, not a guess. Twelve levels run from a gentle 3x3 up to a scrambled 8x8, and every board is seeded, so Reset gives you the same panel back and New Board deals a fresh one.
How to play Light Bulb Grid
- The panel starts with some bulbs lit. Tap any bulb to flip it — lit becomes dark, dark becomes lit.
- The four bulbs directly above, below, left and right of the one you tapped flip at the same time. Bulbs on an edge simply have fewer neighbours to flip.
- Switch every bulb off to clear the board.
- Each tap costs one press. The counter at the top shows how many you have used out of your budget.
- The "Best" number is the shortest solution that exists for this exact panel, worked out by solving the board rather than estimated. Match it for three stars.
- Reset replays the same panel from the start; New Board deals a different one. Clear a level to unlock the next.
Tips
- Order does not matter. Pressing A then B gives exactly the same panel as B then A, so there is no point hunting for a clever sequence — only for the right set of bulbs.
- Pressing the same bulb twice cancels out completely. If you feel stuck, you have almost certainly pressed something twice; Reset costs nothing.
- Work top-down: clear the top row by pressing the bulb directly below each lit one. Repeat row by row and you will end with only the bottom row lit, which is a much smaller problem.
- Corners are the least destructive presses — they only touch three bulbs — so they are useful for fine-tuning at the end.
- On the bigger boards, count the lit bulbs rather than staring at the pattern. If the count is not shrinking over three or four presses, you are going in circles.
FAQ
Is Light Bulb Grid free to play?
Yes. It runs entirely in your browser with no download, no account, and no in-game purchases. Level progress saves on your own device.
Is every board solvable?
Yes. Boards are built by pressing bulbs on a cleared panel, so a solution exists by construction. The game then solves the board to find the shortest one, which is the number shown as "Best".
Does the order I press the bulbs in matter?
No. Flipping is its own inverse and the flips commute, so any two orderings of the same set of presses give the identical panel. The puzzle is which bulbs to press, not when.
What is the trick to solving a lights out puzzle?
The standard method is "chasing the lights": go row by row, pressing the bulb directly beneath each lit bulb to clear the row above it. That always leaves only the bottom row lit, and from there a handful of top-row presses finishes it.
Can I play Light Bulb Grid on a phone?
Yes. The panel resizes to fit portrait screens and the whole puzzle is played with single taps — no dragging, no precision needed.