I am using v5.4.2. If I have a game that was created without Invaders being enabled, and I "check" the Invaders option and Save, will Invaders show up?
After having assimilated a couple of conquered homeworlds, my empire tends to dominate. NPR's don't tend to be much of a challenge, since they tend to be missle-heavy, and by this point my point defenses can easily handle their missle densities. I would like to have a challenging opponent, but turning on Invaders at game creation leads to very long turn times as the Invaders proliferate.