ok, so, a little premise: i play with ai level genious and up. Most of the points are still valid for all difficulty level tough.
This game has LOTS of problems when it comes to races relations, that it ends up killing the fun, unless you want to play as a warmonger
1) Penalty for "you are on a war streak": simply put SCREW THIS. make it WAAAAAAAAAY lighter, unless you INITIATED the war. Basically every race is mad at you because you dont back down and give everything to your opponent, EVEN if you are simply defending yourself. And quite possibly winning
2) You are weak: Oh GOD. Change whatever values you use to calculate threat! instead of a mathematic sum where a ton of trash ships count as a great force, when they are just that : TRASH. Aint that hard, take into consideration defenses, movement capability ( lets say effective mov /3), firepower, and divide it by the NUMBER of ships owned with any sort of weapon, carrier, or transport module. THERE YOU GO.
3) You are ripe for conquering or whatever: Sorry, this is broken, for the very same reason of "you are weak". No, im am NOT ripe for conquest. At the very LEAST make it that considers the forces stationed at the entraces to your empire with a heavy multiplier, Even if i do waste resources placing ships in the inner circles, this hardly goes away.
4) Ai stubborness: ok.... so. they are TOO prone to declare war. and they simply dont know when to give up. Sorry to say it, but learn from Firaxis guys.
IF you declare war. AND you lose 3-5 colonies. AND you lose a solid 6000+ production in ships, AND you lose about 20 population in transports destroyed, and i lose maybe 4 ships, i dont care if you still have more "military power" than me. when i come to you offering to end the war, you friggin say YES PLEASE THANK YOU DONT KILL ME.
Srsly ai NEVER give up. Im kicking his teeth in and he still goes on with "you must be joking" in peace treaty. I dont want him to pay me, i just want him to NOT be so stupid.
Honestly, EVERY GAME at some point turns into a war match. INEVITABLY. People from the other side of the galaxy that i met only thanks to a wormhole declare war on me, and this piles up "war streak" discontent, and then other people declare war....... and so on. I cant play as a pacifist.
The only way is to dedicate from the get go 3-4 calonies to pure ship making and vomit out a ton of useless crap ships. Because AI has the magic power of always knowing your "war potential".
Just a rant, but without some drastic changes, this game got old wayyyyyyyy too quickly. aint fun anymore.