trade hub and population.

[Hellatze]

single player have only lonely engineer and full of biters. i hope he got some "friends" to get talk into.

also trade hub since you "own" the planets.

[OdinYggd]

That's the whole point of the game though, you are alone on an alien infested planet and trying to make the things you need to leave again.

For multiple characters to interact with, use multiplayer.

To trade with other factorio servers, the mod you want is called Clusterio. It allows resources to be transferred from one world to another.