A lattice of wire pieces, every one turned the wrong way, with lightning-bolt sources at some ends and lamps at the others. Turn the pieces until power can run from every bolt to every lamp with no wire left dangling.
How to play
Tap a piece to turn it a quarter turn. Nothing is coloured for being "right": a piece only lights when power actually reaches it from a bolt through wire that meets on both sides, so the glow spreading is your only feedback. Lamps stay dark until the circuit arrives. Work from the corners inward: edge pieces have the fewest legal turns and pin down their neighbours.
Objective
Light every lamp: every wire end must meet another, and power must reach the whole lattice.
Strategy tips
Follow the light. The glowing wire is the part you have already solved: extend it one piece at a time rather than turning pieces at random.
Start at the corners and edges. A tile on the border cannot point outward, which often leaves it only one legal rotation: and each one you settle constrains the tile beside it.
Dead ends are the most informative tiles on the board: a single-arm piece has exactly one neighbour it can face, so place those before anything ambiguous.
A straight pipe has only two distinct orientations, not four. Spotting that halves the work on every straight you meet.