How do you make peace with an AI empire?
 

I have this one AI empire that I want to make peace with. It is down to its Last planet, and I am several dozen times bigger than it. But no matter what I do it wouldn't accept a cease fire even though it has no ships and no defense left. I even tried to offer it a huge planet but it refused the offer. Is it possible to make peace with the AI? I mean, if they know the situation is hopeless, why not accept peace instead of commiting suicide?

Re: How do you make peace with an AI empire?
 

AI: Artificial Insanity.

More helpfully, the ai will only make peace after a number of turns have passed without conflict, or so others have said.

Re: How do you make peace with an AI empire?
 

Look here

Re: How do you make peace with an AI empire?
 

Suggestion: Ignore it. If you're so much bigger than it, you have nothing to fear. If it takes this respite and bites you in the ankle, well, maybe that was the plan all along?

Here's a little tongue in cheek explanation, mostly paraphrased from stuff I read in the Dubious Strategy Guide, without giving away too many secrets.
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Re: How do you make peace with an AI empire?
 

Make sure you havent claimed their system(diplomacy menu, check the BORDERS thing), remove all ships and planets from their system, send in ships for them to kill (which usually makes them feel better if they win some fights). When they are willing to accept gifts, give thm their own system back, give them star charts, give them non-combat tech such as medical or planet boosting.

Generally at the point you descibed I just demand their surrendor but I can see some reasons you might want to leave them there.

Re: How do you make peace with an AI empire?
 

Now see, that one makes them madder as well, as can be seen in the appropriate AI_Anger.txt file (if you wanna cheat and know everything about the race http://forum.shrapnelgames.com/images/smilies/wink.gif )

Whats great is stalemates. That does make them happy. Turtling yourself in with mines at choke points, littering their space with engine destroyed hulks (that maybe easier for bbq's Version of SE4, the engine destroyer skipped shields in older Versions of SE4). Or just send heavily shielded ships with "Don't get hurt" strategy against weak targets.

The AI will sue for peace, sometimes just long enough to pass a mass of satelites.