Haha, the thread title has the words "CIV5 diplomacy works" in it.
In my experience, here are the main Civ V diplomacy points -
- There's no such thing as being nice. You can be nice, but the AI simply doesn't care, or the amount that is cares is trivial compared to how appealing you are as a target and how much stuff you've done that angers the AI.
- Along with this point, there's a human tendency to consider a series of trades that seem mutually beneficial and friendly to be building up good relations with another civilization. That doesn't work. You don't have good relations with other civilizations. You have not-fouled relations - ones where they're not angry yet - and fouled ones.
- Avoid initiating wars, except perhaps super early on or when you're pushing to win the game outright. Initiating wars poisons your relations with most civilizations forever. Things like "you begged me to declare war on that guy" or "I declared war to save your ass and liberated four of your cities" have zero or negligible weight.
- Instead, if you want to go to war with someone, piss them off until they declare war on you. Pissing people off doesn't seem to have any, or at least any significant diplomatic repercussions except that it probably means that the AI you're angering is more likely to make pacts of secrecy against you.
- The number one deterrent to dodging DOW is having a large standing army. The AI will generally DOW extremely quickly if you look vulnerable. You can get away with all sorts of stuff if your army is big enough.
- AI that got "dragged into" a war where the main front is super far away will frequently not contribute to the war at all. The AI is roundly incapable of conducting warfare from another continent. If you do things like shell their random dudes with a naval unit, they'll often conclude that they're losing and surrender to you.
- Don't accept surrender from someone (call them Empire B) whose capital is near yours. Wipe them off the map entirely. If you don't, one of two things will happen. They'll either build back up, a process that typically includes spamming settlers all over the place inconveniently, get ticked at you for being nearby, and re-DOW, or, while they're weak, a third civilization (Empire C) will move in, take their remaining cities, and then get pissed at you for being nearby. (Since they now control cities that belonged to Empire B, which are near your capital.) Oftentimes both will happen, so now Empire C has a bunch of annoyingly-placed cities smushed all up against your borders.
- The only time you should typically trade open borders for open borders is with a civ on another continent when you want to look around or explore that area. Trading for open borders with a not-unfriendly civ so you can conduct war with a civ on the far side of them is a bad idea, since they'll construe your units marching through their territory as a hostile action against them. Trading open borders for open borders for no reason just invites the AI to look into your territory so that they can decide to declare war on you. Trading open borders is not a mutually friendly act, even though it sounds like one. Civ V doesn't have friendly acts.
- If pacts of cooperation have a positive effect on relations, it's negligible. A pact of cooperation is an invitation to the AI to ask for random stuff (gold and luxuries) and to be disappointed when you don't really want to give the person you're "cooperating" with 300 gold.
- Again, friendly acts are negligible compared to relative power. I wouldn't be surprised if you keep better relations with a civ by disbanding one of their liberated workers and using the gold to improve your own position than you get by returning it.
- In general, giving the AI stuff makes them more likely to attack you, not less. Any benefits to relations that a gift has are negligible compared to the fact that by giving the AI something you weaken your position and strengthen theirs, making you a more appealing target.
- The AI is often surprisingly amenable to being asked to do something. In particular, they're often willing to make peace with city-states that they're randomly attacking in exchange for nothing.
The Civ V AI seems a lot less crazy if you flat-out ignore everything that happens in the diplomacy window and pay a lot more attention to what's happening in the world window.