-The default puzzle size is 3\by\.3 (a 9\by\.9 actual grid, divided
-into nine 3\by\.3 blocks). You can also select sizes with
-rectangular blocks instead of square ones, such as 2\by\.3 (a
-6\by\.6 grid divided into six 3\by\.2 blocks).
+Under the default settings, the sub-blocks are square or
+rectangular. The default puzzle size is 3\by\.3 (a 9\by\.9 actual
+grid, divided into nine 3\by\.3 blocks). You can also select sizes
+with rectangular blocks instead of square ones, such as 2\by\.3 (a
+6\by\.6 grid divided into six 3\by\.2 blocks). Alternatively, you
+can select \q{jigsaw} mode, in which the sub-blocks are arbitrary
+shapes which differ between individual puzzles.