In any case you should be able to set a master flag to ban all and sundry varieties of said species that covers all variants and mutations, past, present and future, named and unnamed, specified or otherwise, without let or hindrance, from now and henceforth, by any ways and means necessary, in perpetuity.
Just turn all refugees off? Maybe except the citizen species? And then don't hand citizenship to undesirables.
I do not really understand what refugees are. Are they just pops from other empires that they displace somehow? If so, it seems like having it on is like having a migration treaty with everyone on the map.
Similarly, I guess having a migration treaty with anyone is likely to allow every species in the game to eventually end up in your empire if they go via your migration treaty partner.
I guess it's all or nothing with these refugee/migration treaties.
If you like your main species, it seems to keep them in control, you need to
- have no migration treaties at all, even with empires dominated by species you like
- disallow all refugees not of your citizen race/only give citizen to your own species
- set default rights to No Migration in case you conquer some aliens
Too late for this game it appears, but good to know for next game. It sounds like any migration treaty at all/allowing refugees is just opening the doors to every species in the galaxy.
Am I right in thinking that setting default rights to No Migration for non-citizens won't keep out species coming from a migration partner? Or can you grant citizenship to their main species, and thus allow the treaty to only let in their main species and not any other species infesting their empire? I assumed Migration Controls only applied inside your empire for pops already there, but maybe this can be used to selectively let in species you like.
On a side note, it's 2392, I've conquered all the empires of any note except one, conquered the fallen empire, and everyone else is Pathetic, all techs are researched except the repeating ones. Is there any point in continuing this game? I have never seen a "Crisis" but I am not sure it is worth sitting here for hours building more Urban Districts and Holo Theaters just to see one. There don't seem to be any game-ending victory conditions.