Terrain can be deformed using an assortment of different brushes. For exteriors, the users will have a terrain mesh that they can deform, add water planes, place props, and scatter trees and grasses.
Level creation is done differently for interiors and exteriors. This would allow entering buildings without any transitions of any sort. Roofs could be set to vanish when in front of player view. It is also possible to create buildings using walls, a floor, and roofs manually. The level editor allows users to create new indoor and outdoor levels for their modules.
Here's a sample of what can be done by script:
Recent events showed that it features tons of new functions and script templates as well. The script editor features auto-complete and a built-in help.