Have you already checked out the latest version of Gaia?
This tutorial provides a quick run through of how to create lovely terrains and scenes for your Unity 3D game with Gaia. After we create the terrain with Gaia we then dress it up with CTS, GeNa and a collection of other assets, and finally make a quick fly-through with Pegasus. It gives a sense of what can be achieved with the Procedural Worlds tool suite and workflow. Pleaworkflowibe to our video channel to learn more about what can be achieved with Unity and our tool suite.
You can learn more about the tool and its possibilities here.