This selection determines what happens when you click a point on the map.
If you select "Route," any point you click on the map will automatically have a roadway-based route drawn to it from the previously selected point. The computed route is based on Google Maps’ driving directions feature. Therefore, it might avoid some situations that would actually be ideal for running, such as straight thru uncontrolled intersections in residential neighborhoods. To override its propensity to do that, simply "undo," then click at shorter intermediate distances. With practice, you will gain familiarity with particular neighborhoods, and you will be able to better predict its selections. It will always follow one-way streets only in the legal direction.
If you select "Straight", the map will draw a straight line from your previous point to the point you click. This is suited to situations where you run off-road, such as on a foot path thru the woods. Using the "Straight" option, you must "create your own curves" by clicking several points to follow a generally-curved shape.
Holding the <Ctrl> key while clicking a spot on the map will allow you to track a course "against"
one-way traffic.