So I've reached the end game, and I'm left with a few thoughts on the game.
None of the AI empires did anything about the Unbidden. Sure, they recognized the threat and scrambled to forge alliances/federations, but I didn't see anyone else even try to close the portal.
The post-battle log is missing vital information: while it tells you how much damage was dealt, it doesn't inform the player of ship losses. It'd be nice to see how many corvettes et al. were destroyed.
Furthermore, I wish that doing genetic engineering to allow your species to be comfortable on new worlds didn't make them xenos. Sure, they're technically a new species and all that, but they're still part of the master race. Along these lines, It'd be nice if pop management had a little more nuance, like being able to selectively grant rights to certain demographics.
I'm not convinced that robot pops are actually worth building. The energy maintenance seems like it's better spent on mining stations and fleet upkeep.
The rest of the galaxy automatically becoming aware of a genocide seems broken. The malus for cleansing the Palatial District of the Fallen Empire's ringworld was a bit large considering that a) very few people should actually care about those fallen empire ass wipes and b) it's not like the enslaved population would be able to communicate with the rest of the galaxy. If there were a "I don't care where you go, but you can't stay here" resettlement option, then the mechanic might fit a bit better, but right now it strikes me as heavy handed.
Also, why the hell is it that other empires are so eager to exchange migration access? Seriously, why the hell would arctic dwelling fungi want to move to an empire full of desert and tropical worlds?
Overall, the game is alright, but it definitely could have used a little bit more polish and depth. Mods will address some of these issues, but some (like the end game chug) might be too deep in the coding to be adequately resolved by anyone but Paradox (whom we all know would rather release a subpar DLC)