NFG uses a contextual hierarchy matrix utilized with a Procedural Ray-cast Based spawning algorithm. In other words, objects are created with rules dependent of other layers.
NFG is order dependent, so objects at the bottom layer will be created first and then other layers will proceed. This behavior is beneficial because it allows for the filtering of layers to get excellent results.
Rule Based Generation is a key component and NFG includes a large array of tools for applying these constraints.
Adding A Generator to the Scene
After importing NFG into your project, add a new generator by going to Tools/NFG/New Generator
This will create a new Game Object with a Box Collider and the Natural Formation Generator script.
CLick the "Open Editor" button on the generator script.