Does G&K make the AI somewhat LESS predictable and actually a bit more reasonable?
Examples:
1. If you're peacefully minding your own business but doing fairly well for yourself, even if your neighbor civ is "Friendly" he'll decide to stab you in the back regardless of what sort of trade agreements and whatnot you have in place.
2. During the course of a war (that the AI declared), you repeatedly drive back onslaughts of ridiculous amounts of attacking units, finally the 'lockout' to negotiate peace is up and it's obvious that the AI can't crack your defenses so he offers peace yet pretty much wants everything PLUS the kitchen sink from you to do it?
3. Trade negotiations with the AI are ridiculously lopsided.
- Dear AI, I see you have 80 bajillion incense. Would you like to trade?
- Dear Player, Sure, I would like ALL of your silver, gold, dyes, furs, 30 gold per turn, 3 of your cities, open borders, and a night with your wife. Sincerely, AI
4. Just because the AI is 50 points ahead of you in score... "I don't think such an agreement would be in our best interests at this time." Oh, so you DON'T want a joint declaration of friendship and a defensive pact that would bring me to your aid given that that other AI civ run by that backstabber Napoleon is about to slaughter your ass? Have fun with that.
5. I'm knocking on your capital's doorstep bro. I'm offering you a peace treaty for the fair price of this one city of mine that you previously captured 20 turns ago, but you'd rather be obliterated?
6. My personal favorite: "It has come time for us to lay down our arms." --> Negotiate Peace Treaty --> What would make this work? --> "I don't see any possible way to make this work." Then why the fuck did you ask in the first place?
Theres an explanation for most of these seemingly irrational behaviors, though not always a good one. MOST of the below is from my own personal observations, I'm not the type of guy to go look at the actual code and find the answers to these things. If you really want to know the mechanics of AI behavior, hit up the forums at civfanatics.com, there are many people there who actually dig through the code of the game and find the exact reasons behind various 'irrational' AI behaviors.
1. This is pretty rare in my experience, friendly relations will keep MOST civ's from declaring war on you, but not all. Probably the reason this seems so common is that one of the most likely things to cause another civ to declare war on you is sharing borders with them. All you can really do is keep good relations with them and have a more powerful military than them. I find that having an aggressive civ as a neighbor can actually be a good way to keep them in check, as they will waste tons of resources trying to attack you over and over through the course of the game and its not that hard to fend them off, it takes a lot less effort and resources to defend than attack. I actually like that other civs will declare war and break agreements with you. Maintaining trade agreements or begging for 1 piece of gold to stave off an enemy from attacking you was such a cheesy tactic in Civ4.
2. Peace terms are largely determined by the amount of units you lost versus the amount he lost, as well as your current power relative to his. Cities conquered also seems to play a large role. If a civ declares war, loses most of his offensive force while attacking, didn't capture a city, but managed to kill a large number of your units as well, you likely won't get very favorable peace terms, especially if he has a large amount of defensive units sitting around in his cities keeping his overall power score high. If you want favorable peace terms then you need to kill a lot more units than you lose during the war. I find that the easiest way to quickly end an unwanted war is to fend off the initial attack wave, then take their closest city. If you manage to quickly get a favorable kill:death ratio AND take a city, even civ's that are more powerful than you will sometimes outright offer you peace plus a lot of extra goodies. Usually this is only possible with a military tech lead, but an even military tech level and good tactics can work as well.
Unfortunately when a far away civ randomly declares war on you, there is usually little you can do but continue killing off their units until they get bored. Fortunately the AI is not very good at long range warfare so while it may be annoying, it rarely poses any real danger. You can also bribe their neighbors or other civs between your land and theirs to declare war on them. This will lessen the amount of units that they send at you, and I find that civs that are in multiple wars are much more open to fair peace treaties, but that might just be my imagination.
3. There is actually a lot more thought behind AI trading behavior than it may seem at first. Unlike previous installments, the AI will no longer do stupid things like accept iron for a luxury resource when they are in the modern age. They also seem to actually take in to account their need for additional luxury or strategic resources when determining the value of a trade. If they have plenty of happiness, they aren't going to give you a 1-to-1 trade, because your luxury resource has little value for them. Relationship status also factors in to trades, if a civ dislikes you, it doesn't matter how much they want or need what you are offering, you aren't going to get a fair deal. Different civs have different personalities and thresholds for these things as well. One civ may be willing to make a 1:1 luxury resource trade at neutral while another won't do it unless they are pleased with you, while yet another won't do it unless they are friendly with you. AI trading behavior only seems so bizarre because its very different from Civ3 and Civ4 where you could basically fund your entire empire off trade-raping other civs, and because we don't get to explicitly see the logic behind WHY a civ will only accept a lopsided trade. You can infer a lot though if you pay enough attention.
4. I don't even understand how you came to this conclusion. I have been offered declarations of friendship and defensive pacts by civs ahead of me in score many times. I won't pretend to understand all the mechanics behind what makes a civ offer or accept these declarations, but I highly doubt points have much to do with it.
5. Again I rarely encounter this situation, but when this does happen it likely has a lot to do with what I mentioned in point 1, specifically the number of units you lost versus what they lost. Taking cities without a military tech lead often means you lose many more units than they do, so even though you captured several of their cities and have a military power advantage, the AI may actually think its winning the war. Silly? Sure. But there is only so much you can do with AI programming. There are probably other factors at play here that I'm simply not aware of.
6. I've never seen this. I can only assume that they are willing to make a peace settlement but only for a price, and you don't have what they want. I'd venture to guess that the AI is programmed to prompt for a peace settlement on certain conditions and it doesn't check whether you have enough to give them to end the war. Probably a bug, since I also know that the AI will come to you with peace terms laid out in advance sometimes. Who really cares though, this doesn't affect game play at all.
Bottom line is that the AI can't possibly come anywhere near the intelligence or reasoning powers of an actual human being, its all based on numbers and formulas, and the AI can't be programmed to handle every possible scenario, so it is inevitable that you come across situations that don't make sense. While some things my seem weird to us, there is always a rationale behind it, and most of the time these irrational situations are due to the AI having to react to a situation it wasn't really programmed to deal with.