Nice idea with connecting circuit elements, click sound also nice one. For now tactics to complete level is "click each line, if it can rotate, rotate until it lights up". Would be better if the player could see the difference between rotatable lines and static. And of cource, static and dynamic lines should be highlighted if connected with battery. And, as mentoined, two way direction.
Also, second level has a bit different light bulb, without highlight, And two last ones levels don't highlight light bulbs, i clicked all the lines and did not find something more