They have surrendered to me.

I pushed them back to their home world, jumped in and took care of what fleet they had left, then they gave up.  I kept playing and destroyed their homeworld anyway.

i've had them quit on a multi-star map before i even moved into their main system.

They quite frequently surrender when you take their homeworld and they have an unfortified asteroid behind it.

To be honst, I was playing an insane game of 9 unfair ai, it didn't give up until I hit their last planet. However, they didn't surrender individually each time I defeated their fleet and all of their planets.

I was wondering WTH was going on. Huge map, 9 AI's, hard difficulty. They had 9 planets, and an entire system to themselves. Just like you said, broken picture on the diplomacy tab. I figured they got wiped, but scouts kept reporting planets under their control and large fleets in their systems.

I have already sent a question to support@ironclad.com on this issue here is the portion for this issue and their response:

Also in the saved game I sent you the resources where messed up before the computer player gave up. I was just trying to get more planets messed up in resources. And if you look at the computer player he has at least 10 planets probably more I haven't sent out scouts since close to the beginning of the game. Why did it surrender? Just another bug I have noticed this before but never this bad.

Here is their response:

"AI players have surrender thresholds that factor in relative fleet size, income rate, number of planets compared to the player, and fraction of their own planets they have lost; it is likely that these thresholds were satisfied once you started taking their planets."

This seems not to be correct since I have seen the AI surrender with a decent sized fleet still and over 20 planets, but as far as ironclad is concerned they are not planning a patch for this.

None of this agrees with what I've been observing in Sins 1.16/Entrenchment 1.02 so far. Even when massively behind the player, the AI does not surrender. I've literally had a situation of me owning 14 planets against the AI being stranded with no fleet on only their home planet, with their resource asteroids bare and no orbital structures whatsoever, and still the AI would not surrender.

I wonder if the routines that decide whether or not the AI surrenders could somehow be exposed to modders? I'd have a go at it for sure. Maybe all that's missing is a little bit of fine-tuning.

 in sins 1.16 and entrench 1.02, the ai is still messed up. i was playing a 5 star custom map, and i had just finished crushing the very last construction ship of the first race (vasari) before heading off to a new system to take out another. id been sending scouts, so i new this system had only a few enemy plants colonized (i had done only 2 ai + me in the 5 star map, just to check it out ) so i phased in on one of the three planets the advent had, and they immediately surrendered.

1) i had not even started attacking the planet.

2) this was not its home planet, not even its home star system!

3) something needs to be done

EDIT: to be honest, they were on medium, but still, this was just not right.

Another vote for this.  Give us the option to disable surrender.  Cool for some people, not for me.  I'm tired of taking AI #1's homeworld only to have #2 throw in the towel with them when their combined might is still greater than mine.

Ahhh this is wierd...

I had a multiplayer game, where we had a player in the pocket position inbetween myself and allies , It was right at the start and he had just captured his first asteroid with the Egg Cap.

He then minidumped (confirmed) , and the AI immediately surrendered forcing the game into 3v4 , which was mildly annoying.

In 1.16, I was playing on an absolutely huge custom map, and I spammed Novaliths and shoved three fleets along with a bunch of insurrections because of the research deep into their territory.  While they weren't attacking, it took them 2 hours to figure out they were dead.