3 Form a single closed loop out of the grid edges, in such a way that
4 every numbered square has exactly that many of its edges included in
7 Click on a grid edge to mark it as part of the loop (black), and
8 again to return to marking it as undecided (yellow). Right-click on
9 a grid edge to mark it as definitely not part of the loop (faint
10 grey), and again to mark it as undecided again.
12 When you have mastered the square grid, look in the Type menu for
13 many other types of tiling!