Couple of ideas I've had...
GalCiv3 Forums
I've had a few ideas while watching the dev streams over the last few months - don't know if any of these are mod-able, if so great, but if not is there a way I can send them to Stardock for their consideration?
1- Give the game AI the option of breaking up into 2, 3 or 4 different governments if they are losing a war. This would be a different 'option' to simply surrendering to another player (which tbh I find a little boring). Not saying the current surrender option should not be on the table but breaking up into a number of independent entities would be a lot more interesting. Some or all could sue for peace seperatly, some or all could continue the fight anyway, some or all could fight each other to 'reunite the empire'. I'm thinking of Russia at th end of WWI - Whites vs Reds. The different sides would use the same tech tree and ship style which should simplify things a little.
2- I'm pretty sure that someone suggested the idea of allowing minor races to join your empire voluntarily during one of the dev streams - a really great idea which I think should be added. On top of that - how about if you could 'liberate' a minor race if they have been conquered by someone else. So you would launch a planetary invasion as normal, and if you win, instead of gaining the planet yourself it brings back the minor race? You could make it so they then have to direct all their trade to you or something as a concession. This allows the player to maintain more flavour in their galaxy late game - I find the late game can get a little 1 dimensional, this would go a long way to solving that. Again, to be clear, you could still just conquer a minor race as normal if you prefer.
3- Similar to option 2 but with major races, here's an example - you're playing as the Terrans, the Drengin and Arceans are at war and the Drengin are tearing the Arceans a new one - taking several of their planets. You jump into the fight to help the Arcean's by invading some of the worlds the Drengin have taken from them - it would be good if you had the option to give those worlds back to the Arceans. I know this can be done through the diplomacy screen but I think a separate UI and game mechanic for this would be very cool. Again, you would still have the optioN to keep them for yourself as normal.
4- We'll be back! What if a previously defeated civilisation could return to the game under the right conditions? Here's an example - The Drengin defeated the Krynn several game weeks/months ago, but a number of former Krynn worlds have very low approval ratings. So what if 2 or more worlds that are close enough to each other get an approval rating low enough it creates a widespread rebellion over a handful of worlds and the Krynn rise up and return to the game. I'm not talking a wholesale reversal so they get back exactly what they had before the war with the Drengin started, but 3 or 4 worlds rebel and reform the Krynn Syndicate. This also brings up a related idea of governments in exile - if a government exiles itself to you then if you invade some of their former worlds you can reinstall them and bring that race back into the game.
All races used are simply for examples - these mechanics would apply to all races in game.
I think these options would do three things - a) make playing a benevolent race a lot more interesting with far more options for expansion, 
create a lot more fluidity and surprise late game and, c) make an already incredible game even better!
For me the one thing that galciv is missing is unpredictability in how any game develops. The major events go a long way to helping that, but late game can get to feel a little like knocking over dominoes - it's a bit to formulaic. Allowing the return of minor and major races after they have been defeated, either through rebellion or liberation, would add a whole new dynamic imo.
