Side Effects changed the licensing terms of Apprentice HD and added fbx export and is now targeting Indie game makers. http://www.sidefx.com/index.php?option=com_content&task=view&id=2853&Itemid=66 If you are not familiar with Houdini there is a dedicated training site for using Houdini a games pipeline: www.gametutor.com…
The terrain is generated in houdini from a heightfield and converted to an unreal mesh. The green and yellow you see are just proxxy geo spawned from houdini showing you where the fields will be, most of the heavy lifting from this tool has been done in houdini and just applied in unreal engine :)
Houdini for games is only getting better. Houdini Indie, Houdini Engine - really great value for all levels - hobby, Indie all the way up to AAA... as for Terrains, have a look at this MasterClass : https://www.sidefx.com/index.php?option=com_content&task=view&id=3095&Itemid=410