Small worlds with masses ranging from 0.0001 to 0.15 Earth masses. Most are large enough to sustain hydrostatic equilibrium (they are spherical), and may have geological activity due to tidal stresses. Many are relatively passive worlds though, and rarely have much of a sustainable atmosphere.
Small bodies still in the process of forming. Their surfaces are often partial to completely molten, and their atmospheres are typically thick with hydrogen and helium. They are generally found in young solar systems.
Apart from their size, these world types are very similar to the ProtoActive worlds of the Terrestrial Group, and their names are similar. If they end in -ian, they are Dwarf Terrestrial worlds, those that end in -ic are Terrestrial worlds.
Such worlds do not sustain continuous geological activity. Their surfaces are largely unchanged since their formation.
These worlds sustain regular or intermittent geological or geothermal activity due to temperature differences caused by highly eccentric orbits.
Note that WorldGen does not currently support elliptical orbits, so simulating these world types is not yet possible.
These worlds sustain geological activity due to tidal flexing. The level of activity can range from constant resurfacing to intermittent geothermal activity, such as cryo-volanic outgassing.
GeoCyclic worlds possess an active geology which occurs in a cyclic basis, often over periods of hundreds of millions of years. Though various mechanisms may be responsible, this is often caused by a slow build up of geothermal energy which results in a short phase of activity.