7 Worlds. Arkerion

Arkerion: a wandering rocky, man-made planet. Life and even a highly advanced civilization once lingered on its surface. But a catastrophe occurred: it was ejected from the system due to a close encounter with another star. The inhabitants discovered the impending threat and focused all their efforts on preparation: they built deep underground cities and transformed the planet's surface into a solid shell to protect it from external radiation and internal heat loss. The shell is studded with needle-like watchtowers, which can be used to automatically destroy asteroids dangerous to the planet. The doomed civilization digitized its biological bodies and consciousness and preserved itself deep beneath the surface, hoping to one day be resurrected with the help of other intelligent beings, leaving behind only an endlessly repeating distress signal...
Fortunately, humans on Earth heard the signal and discovered the planet, allowing them to revive the first dormant aborigines and help them find a new home among the already discovered worlds. In exchange, earthlings received physical teleportation technology, which significantly accelerated the further exploration of space.