I got my game settings to be as realistic as possible (i.e. progress is as slow and habitable planets are as rare as possible):
Research is very slow, habitable planets are very rare, uninhabitable planets are abundant, star systems, asteroids and anomalies are also very rare and the galaxy size is immense. The AI was set to 100% natural ability, 100% income and 200% processing power ("Bright")
I did this because I wanted a refreshing change of pace - every planet would matter and a single colony could mean the difference between victory and slavery and a single tech could mean that a war is won instead of lost.
4 out of 4 games I played like this so far the AI tries to play like we are playing on a medium sized galaxy full of habitable worlds - I was in a corner with one class 7 colony and simply bought class 3/4 worlds from AIs in exchange for a few techs and some loose change. The problem is, however, that this world was one of three colonies that AI had in the entire cluster and beyond and they churn out fighters and constructors without an economy to support the fleets.
I kept buying their colonies (the few they had) and conquered minor races (rushed to Planetary Invasion with 100% research spending) and then built up research facilities on conquered worlds and was pretty much the undisputed ruler of the galaxy. Drengin, for instance, were toiling to get Stinger IV giving me the "Be afraid!" line every 30 turns while I had already gotten Aereon missile defense and invulnerability fields. In the latest game I have 55% of the galaxy's population (nearing a trillion), 60% of the influence and a single capital ship of mine can handle an entire enemy civilization, which is equipped with swarms of tiny sized fighters, some of which still have particle beams.
You'd think the mega event that makes all the worlds within 2 parsecs of their home system class 9 would help, but they either sell those for loose change as well or don't even touch them. I have started to lift up some civilizations by giving them outdated tech (by my standards) and having them destroy the rest of the interstellar community because dominating things started to get boring. I gave up on 3 games after it became obvious that I was invincible and I'm close to doing so with the fourth as well.
One game was almost a challenge at one point when the Drath decided I was becoming too powerful and warred me, but their worlds were protected by a single fighter and I just bought transports from nearby colonies and got their worlds (all 3 of them) while they were busy fighting wars I paid them to fight.
Is there a way to make the AI think better when it comes to this or do I have to give it 200% abilities and resources or change the game settings?