I really like the direction you’re going with. The idea of having threats that create gameplay outside the main planet feels like it could add some nice tension.
I’m definitely going to explore how something like this could fit into the current mechanics. At the same time, this kind of concept makes me think about the protagonist’s starting point and backstory - like whether Earth was already conquered, or if these space vermin nearly wiped it out and the Overlord was the one who saved it, essentially becoming the leader of Earth before going on to conquer the rest of the galaxy.
Because it’s such a significant part of the story, I feel like it might need some gameplay connection rather than just being pure lore. I’ll have to think about how to tie it in properly.
Feel free throwing more ideas on this.