Regarding AI behavior:
I'm not sure exactly what it is, but some combination of the game updates, me giving myself and all random-gen empires six ethos points (rather than four), and a mod that adds additional AI empire attitudes has done some wonderful work.
We're all familiar with the standard experience, the two types of AI. There were all the strong assholes that invaded and annexed everything, and there were all the weak assholes that banded together into federations. Give a game a few decades and the entire map would consist of the former's super-blobs and the latter's federation-blobs.
I'm not getting that in my current campaign. Well, I'm getting lots of hostile assholes, but that's because I'm playing xenophobic fascist space elves. The AI-AI interactions have been really cool. In a 3500 star galaxy with ~30 starting empires and four fallen empires (no advanced start ones; they're all random-genned so they all get the increased ethos and trait points and slots to make them more distinct), there is either one or two federations, and it/they have only a handful of members. Two of the strongest blobs in the game are "federation-builder" types that instead took the conquest-through-diplomacy route by talking all of their neighbors into vassal status and then annexing them. Wars between AI happen regularly, but not at an incredibly high rate -- usually it's just two or three ongoing at any given time.
More importantly, remember what I said about playing xenophobic fascist space elves? I've got two fairly close allied empires who've backed me up and been backed up in turn. The kicker? They're
also xenophobic military/spiritualist types, and they tend to be on the far side of my most hostile neighbors. That's a really interesting interaction that didn't seem to happen in my earlier campaigns.
However, it has also highlighted two problems: border friction is still fucking absurd, and there's no real allied state between mutual defense pacts and full federation. The former is more important. As I and one of my purging buddies took bites out of one of our rivals, we eventually had our respective territorial salients make contact. Instant -50 or some shit to our relations. I reiterate: border friction is
fucked. We and they have been working together to exterminate inferior alien filth for over a century and the fact that we can now have our fleets wave at each other without needing to start a war against a common neighbor instantly nukes relations?
IMO border friction should be extremely minor unless two empires
already have negative relations. Otherwise your allies are only safe if you federate (fuck that) or are on the opposite side of the galaxy (at which point why bother allying, it's not like you'll get military support).
Clearly my empire and theirs have some sort of mutual respect or understanding. Yeah, the other side are still xenos heretics, but they kick as much ass as we do and are equally honorable, so how about we meet in the middle and then start pushing out in other directions? LOLNOPEGOODBYRELATIONS
On an unrelated note, that common neighbor we've been attacking?
The 60k are my purging buddies, the two other fleets are random neighboring powers. These guys have five separate wars being waged against them at the same time.