How about we do not have special underground cities but we should have special underground improvements because life underground is different from aboveground.
More Resources:
Magma [Power resource *Volcanic Power* (Theoretical Geothermal powersource-Total Annihilation]
Types of underground terrain:
Granite [Mineral-rich]
Sandstone [Trashland (wasteland); fertile]
Soil [Fertile]
More Resources:
Magma [Power resource *Volcanic Power* (Theoretical Geothermal powersource-Total Annihilation]
Types of underground terrain:
Granite [Mineral-rich]
Sandstone [Trashland (wasteland); fertile]
Soil [Fertile]
Comment