Undercliff

Undercliff buildings are buildings that can only be constructed under the cliff at the lower ground levels, or are clifftop buildings that can help you construct buildings at the lower ground levels. They are crucial for allowing the player to prepare or even transition into the mid-late game.

Their UI category color is orange-red.

Most of them are unlocked at Honor Points level 11, but some of them are unlocked at Honor Points level 19.

Buildings
These are unlocked at Honor Points level 11 These are unlocked at Honor Points level 19:
 * Engineering Hangar
 * Small Dock
 * Dock Station
 * Capsule Generator
 * Ore Mine
 * Splitting Reactor
 * Geothermal Station
 * Capsule Battery Station
 * Satellite Dish

Tips and Tricks

 * All Undercliff production buildings reduce global ecology. Keep that in mind when reorganizing the clifftop.
 * Notice that Undercliff Drones can only return to their "host" cliff city when returning from the Undercliff region. E.g., the Undercliff Drones of City A will always deliver goods from/to City A and the Undercliff region and return to City A, but never go to City B.
 * Undercliff Drones also will not work at night, to refill their anti-radioactive layers
 * Geothermal power from the Geothermal Station and the Capsule Battery Station can easily and efficiently replace the Nuclear Power Plant, allowing players to easily generate a lot of power for their clifftop cities.
 * The replacement of Nuclear Power Plants can help restore Ecology, which can be useful to sustain the initial global Ecology loss from the first production buildings.
 * Eventually, the clifftop should have a lot of parks and/or air purifiers to offset the global Ecology loss from having many Undercliff production buildings.