Light GridPuzzle ยท Brain
How to play Light Grid
Light Grid is a lamp-placing logic puzzle. The board holds white tiles and black walls, some of them numbered. Put a bulb on a white tile and it lights its whole row and column until a wall stops the beam. Your goal: light every white tile, never let two bulbs shine on each other, and give each numbered wall exactly as many bulbs on its four sides as the number says (diagonal bulbs do not count).
Click a tile to place a bulb, click again to mark a dot (a tile you know cannot hold a bulb), and once more to clear it. Right click or a long press marks a dot at once. Lit tiles glow warm, bulbs that clash turn red, and a numbered wall turns green when it is satisfied. Every board is generated with exactly one solution, so there is always a way to reason it out.
The 30 levels grow from 7x7 to 15x15 with fewer numbers as you go, and levels keep coming after that. Undo any move, restart a level, press Check to see wrong tiles in red, or use Hint to ring a tile that must hold a bulb (the first hint of a level is free, more come from an optional video). Finish a level without help for three stars. Progress, stars and best times are saved on your device. No download, no account.
Controls
Click a tile: bulb, again: dot, again: clear. Right click marks a dot. Arrows + Space move and place. Z undo, H hint, C check, R restart.
Tap a tile to place a bulb, tap again for a dot, long press marks a dot at once. Undo, Hint, Check and Restart buttons sit under the board.
FAQ
How do bulbs light the board?
A bulb lights its whole row and column until a black wall stops the beam. Every white tile has to end up lit.
What do the numbers on the walls mean?
Each number is how many bulbs must stand on the four sides of that wall (up, down, left, right). Diagonal bulbs do not count.
Can two bulbs light each other?
No. If two bulbs can see each other along a row or column they turn red and the puzzle is not solved.
Does every level have one answer?
Yes. Every board is generated with exactly one solution, so it can be worked out by deduction. Use Check, Hint or Undo when you are stuck.
Is Light Grid free?
Yes. It is free to play in your browser, with no download and no account.
Can I play on my phone?
Yes. It runs on phones, tablets and computers. Tap a tile to place a bulb, tap again for a dot, long press marks a dot at once. Undo, Hint, Check and Restart buttons sit under the board.