A Class E planet makes the transition to Class F once the crust and core have begun to harden. Volcanic activity is also commonplace on Class F worlds; the steam expelled from volcanic eruptions eventually condenses into water, giving rise to shallow seas in which simple bacteria thrive. When the planet's core is sufficiently cool, the volcanic activity ceases and the planet is considered Class G.
- High attrition damage to units outside Pressure Domed Cities.
- All facilities require Pressure Dome upgrades or suffer damage.
- No Naval Units
- No Fishery or Waterport
- Increased chance of Volcanic Events.
- Mines produces x2 Metal
- Geo-Thermal produces x2 Energy