No edges
Ten boards from 4×4 to 6×6 with 4 to 6 threads, and the cloth has no edges.
Lead a thread off the right side and it comes back on the left; off the bottom, and it comes back at the top. In the game the faded cells around the board show the other side. Several levels add fences too.
This twist takes away your best friend: corners. On a board without edges every cell has four neighbours, so forced moves are rarer and buttons that look far apart may be neighbours across the border. Before you draw, check both ways round. The no-edges guide shows how to find your footing.