I Intentionally added the word instant there for a reason, the idea is suppose to delay it in a sense that the father a CS is the less of an impact you should have on it. Just a little change to add some more depth to a bland mechanic.
About the AI, I think we really need to look at a diplomatic victory from a perspective that none of the AI want you in or would vote for you unless in dire situations. Which would mean that diplomacy victory should revolve around CSs and competing with the other Civs outside of war.
So I have a general idea of how I feel Diplomatic victory should work. DOW and capturing a CS would make it very hard to get Diplomatic win. You would have to compete via trade deals, protection, embargoes, and spies with other civs to gain the influence. As an example Instead of quests like get the most culture in 20 turns they would have stuff like set up an embassy in this Civ near us or have open boarders with the Civ that touches our CS boarder. Stuff that actually makes you have to play with the AI and get them to do things.
I would leave a lot of the voting functionally the same, extra delegates for the wonders and hosts but I would just change the method to rely on city states and create a diplomacy thing around them. The AI does not want to lose, it almost never makes sense for them to vote for you.
Well they 'wont' vote for you. If you have a diplomat in their capitals; you can discuss UN issues with them. On the issue of UN election, they will flat out refuse to vote for you,but can be bribed to vote for another Civ. Why this mechanic is even inplace I'm not too sure as you're unlikely to be taking votes away from a likely UN winner if all the AI always vote for themselves. This mechanism seems unfinished and could be patched later.
So anyways, there is that mechanic in place.
To go off on a tangent, if we want the AI to do anything other than vote for themselves *as some have complained* then the mechanic needs to be clear, and it maybe should just be an automatic vote split.
Before we get to how vote split is determined, I also agree the Civs themselves to increase their own delegate count, while nerfing the delegate count from city-states; perhaps leave it as 1 from CS instead of the current 2.
That will rebalance how votes are counted. On top of that, Civs themselves could earn extra delegates as the game progresses.
Extra votes could come from
- Globalization (diplomat in another civ's capital add 1 delegate - same as it is now, but this tech will be REQUIRED for UN victory) Once tech is researched; the bonus applies to all Civ; with the Civ researching receiving a bonus 2 delegates.
- a Social policy finisher?
- a National Wonder?
- A flat boost of delegate count for UN by an extra delegate
-
Extra votes removed from City states
- 1 delegate instead of 2
Once the votes have been slightly rebalanced; we may also consider vote splitting in situations where your cultural is influential to another Civ and their share their own ideology.
It can be on a sliding scale, where they split more of their votes your way if you meet more of the requirements.
This way, it will be another mini-game /sidequest with a set structure and rules, and not opaque which leads the human player to immediately accuse the developer of crafting an AI that is anti-human, even if there's perfectly legitimate diplomatic reasons programmed in.
At the same time, we want to avoid AI throwing entire blocks of vote against the human player just for 'challenge' as it opens the door for statelmated games, frustration and domination-lite situations that we've so far avoided in Civ5.