Net
<p>
Rotate the grid squares so that they all join up into a single
connected network with no loops.
<p>
Left-click in a square to rotate it anticlockwise. Right-click to
rotate it clockwise. Middle-click, or shift-left-click if you have
no middle mouse button, to lock a square once you think it is
correct (so you don't accidentally rotate it again); do the same
again to unlock it if you change your mind.
<p>
Squares connected to the middle square are lit up. Aim to light up
every square in the grid (not just the endpoint blobs).
<p>
When this gets too easy, select a 'wrapping' variant from the Type
menu to enable grid lines to run off one edge of the playing area
and come back on the opposite edge!