Objective / Rules - Light up every square in the grid. - A number in a square indicates how many bulbs share an edge (but not diagonally) with that square. - A square is lit if it's in the same row or column as a bulb, as long as there are no black blocks between them. - No bulb may light another bulb.
Mouse Usage Note: only when supported by your computer/device/browser/etc. Left-click = bulb >> X >> none. Right-click = X >> bulb >> none. Clicking a clue square will 'tick' it.
Checking If you click 'Check' the system will check for incorrect squares. If 'Show mistakes when checking' is checked they will be marked in red. If 'Highlight clues' is checked any clue where the correct number of bulbs surround the clue will be highlighted - this does not mean that the answer is correct.
Show Dots If you click 'Show dots on lit squares' the system will show lit squares with the addition of a dot, which might make the lit squares easier to see.
Uniqueness Each puzzle has exactly one solution, which can be found using logic alone and no guesses are ever required. If you think you've found another solution, then please double check the rules.