Slide the grid squares around so that they all join up into a single connected network with no loops.
Click on the arrows at the edges of the grid to move a row or column left, right, up or down. The square that falls off the end of the row comes back on the other end.
One square is the source: the black box the power comes from. It never moves — the row and the column it sits in cannot be slid, which is why no arrows are drawn beside them. So a square sharing the source’s row can only be shifted by sliding its column, and vice versa, and the network has to be built up around the source where it stands.
Squares connected to the source are lit up. Aim to light up every square in the grid (not just the endpoint blobs).
Connecting across a red barrier line is forbidden. On harder levels, there are fewer barriers, which makes it harder rather than easier!