Draw lines along grid edges so as to divide the grid up into connected regions of squares.
Every region should have two-way rotational symmetry, should contain exactly one dot which is in its centre, and should contain no lines separating two of its own squares from each other. A region satisfying all of these requirements will be automatically highlighted.
Click on a grid edge to add or remove a line. Right-click on a dot and drag the mouse to place an arrow in a grid square pointing to that dot, to indicate that you think that square must belong in the same region as that dot. Right-drag an existing arrow to move it, or drop it off the edge of the grid to remove it.