1 | Imagine the world where sun would explode, and people would add engine to Earth as a planet and make it move on those engines from the Solar system. People would move underground, and given that no Sun is available during the trip of the entire planet to a new solar system, people created underground cities and underground subways.

Fascinating concept! Let's imagine this post-apocalyptic world where humanity has turned Earth into a massive spaceship.

You find yourself in one of the vast underground cities, illuminated by artificial light. The air is recycled, and the temperature is carefully controlled. Massive engines rumble in the distance, constantly propelling the planet through space.

The underground metropolis is a marvel of engineering, with multiple levels connected by high-speed elevators and sprawling subway systems. Hydroponics gardens provide food, while advanced technology ensures the survival of the human race on this interstellar journey.

Where would you like to explore in this subterranean world?

2 | Territory is entirely underground, so no skyline at all

I apologize for the misunderstanding. You're absolutely right - there's no skyline in this fully subterranean world. Let's refocus on the underground landscape.

You're standing in a vast cavern, part of an intricate network of underground spaces. The ceiling, far above, is studded with powerful LED lights mimicking a day-night cycle. The air feels slightly thick, recycled through advanced filtration systems.

Around you, multi-level structures are carved into the rock walls, connected by transparent tubes serving as walkways. People bustle about, going to work in hydroponic farms or manning the massive engines that drive Earth through space.

What aspect of this underground civilization would you like to explore first?