The problem i always had with the AI in Galactic Civilizations 2 would be partly due to my play style. I would always focus on research, economy, and industry so my exchanges with the AI would go something like this.
AI: Hey you! i see you don't have as many ships as me!
Me: Yeah so what?
AI: I hate you now! give me everything you own or else!
Me: What, no?! i'm not going to give you every credit and planet i own you moron
AI: Fine war it is then
Me: You do realize i am number one in Technology, Economy, and Production power right?
AI: You a horrible person. You must die!!!!!
I would use my better resources to build a fleet of ships designed to counter everything he had. Since the AI focused on number of ship more than quality it was easy to build ships basically immortal and stop everything at my border while i continued my empire building. I didn't always feel like being forced to absorb more territory. Then things would go like this:
Me: Hey i've killed literally like a 100-200 ships of yours i haven't lost a single unit. you want peace?
AI: You are losing this war, it is only a matter of time now. But if you want peace we can do that for oh say.... 4 of your planets! Muahahahahaha
Me: Fine i will pin you on at least half your planets
AI: Nope we are still winning, you are horribly weak and we don't care we haven't been able to kill a single ship while crippling our empire throwing ships at you.
I pretty much had to strip 3/4's of there entire territory of ships for the AI to finally want peace. and usually just barely at that. It never mattered how well there PERFORMANCE in the war was.
I think the AI really needs to do the following (i still notice some of this issue in FE, at least the last time played)
- Keep track of its Wins to Loss ratio
- A value system placed on units, maybe even a tiered system of value
- Your best combat units like champions or best equipped infantry, have a higher value and when they have a horrible Wins:Loss ratio (even if you have more overall units) maybe you need to reevaluate your standing in this war
- Weaker units like scouts and settlers you don't expect to win would have a much lower value or be in a different tier entirely. That way killing 15 scouts wouldn't tell the AI its time to pack it up and go home, but instead tell it your enemy is holding the line well or you are not holding your battle line well