After Survival

So a group of us have now "survived" meaning we killed all the aliens on all the planets, set up bases, made numerous ships. What is there to do now? Is there a way to make this game progressively harder? For example: being raided by aliens or having the aliens take back their bases and such. Otherwise this becomes a dead end game and gets very old very fast.

Suggestion: The initial drones hitting your base ends after a few rounds, keep having them come and get stronger after every...

After Survival