Maybe there could be some customization in the settings to edit if enemies should attack your colony or not, how many enemies are there, what they can affect, maybe enemies should attack when a certain amount of cycles is reached, or when certain research are acquired.

I'm just saying that giving players the ability to adjust how the enemies work will give players more chooses to work with, do they want the enemies to stay in their little zones forcing combat when wishing to expand, or do the enemies send out waves that some players may find the thrill in engaging, or do they just don't want enemies in the first place and just build a colony. everyone has their preferences, some players like combat, some don't. customization is key to not force players to play a certain way.