Fences
Ten boards from 5×5 to 7×7 with 2 to 6 threads, and one new rule: a dark bar between two cells is a fence.
A thread can’t pass a fence — it has to go around. Everything else stays the same: connect matching buttons, don’t cross threads, cover the whole cloth. The levels start gentle and end with boards that need real planning.
Fences make the board smaller than it looks. A cell boxed in by fences on two or three sides behaves like a corner, and that is where forced moves hide. Treat every fence as a piece of border. More tricks in the fences guide; the other twists are on How to play.