I’m imagining so many diverse civilisations… Some living in the poles, with rotating walls and mirrors to control the heat. Some civilisations living underground. Some are nomads, moving constantly (would work really well for small planets with a very long day). Some civilisations live near volcanos and use geothermal heating to survive the long nights, and hibernating in deep caves in the day.

Later when nuclear energy and heatpumps are invented/discovered, more of the planet becomes inhabitable, with extremely fast underground trains to facilitate travel.