Why Are Some Cities More Vulnerable to Spies?

The AI will go where the science is, which is usually (not always) your capital. If you make stealing in your capital too difficult, the AI will move its spy to another city with good beaker production. I've had many a game where I had a level 3 counterspy in my capital, and got notice that "X technology was stolen from city Y. You might consider putting a spy in city Y."

Just for the sake of adding to the conversation, I recently played an Immortal game on a small Japan map. 6 Civs, small map. I was Indonesia.

After surviving an initial onslaught from Mongolia and Alex, I took a nice tech lead, and my second city, which was on a river, quickly grew to be a large science city. I had multiple AI steal technologies from it and had to place a spy there to counter.

It may be that that second city (particularly after I flew into Research Labs) produced more science than any AI city on the map. I have no idea about whether this varies with map size, difficulty level, or other factors, but that second city got hit pretty hard by spies.

Asklepios said:

http://civilization.wikia.com/wiki/Espionage_(Civ5)

Broadly, the more science a city is producing, the quicker it is to steal technology from, However security buildings provide some defences, as to counterespionage agents.

If you are looking to steal tech, aim them for the ones with the most star ratings, as they'll be the highest science producers. If you are ahead in tech, don't bother as you can only steal a technology they have acquired but you haven't.

If you want to prevent tech theft (or at least improve chances of doing so) place them as security in your highest science cities. Bear in mind this is usually not optimal use of spies though, and unless you already have 100% alliance with all city states, you're better off using them for that.

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I think that the buildings just delay how long it would take to steal from you, and the counterspies don't affect the length, but increase the likelihood that the spy will be caught and killed when he's gathered his intelligence (which is nice because you then forgive the AI and get a diplo boost). So the buildings will make life a pain for the AI, but you won't get your diplo boost.

chazzycat said:

its all about the percentage of the empire's science output in that city. So, the best possible stealing target would be a player with only 1 city. Basically, the best target is the tallest capital in relation to the size of their other cities (and is ahead of you in tech).

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It has literally nothing to do with that. Try reading what people that actually know how it works say instead of spreading misinformation and make this forum a better place for all of us.

I have never heard of what you describe, but to be sure, I tested it, and it's wrong. In reference to my previous post, the value of "c" is based on the cost of the tech for you. The AI's number of cities has absolutely no effect, nor does the percentage of their total science in the target city.



On another note, the absolute best thing that can happen is this. On the turn your spies establishes surveillance, there are only cheap techs, like optics, available to steal. Before the spy steals it, the AI researches an expensive tech from another tech path. The time to steal is not increased, and you get to steal an expensive tech very quickly.

So maybe in rare situations, when you still don't have optics/compass/navigation, it might be worth it to spy on someone who's on par with you in the bottom tech path but behind otherwise. They won't have any expensive techs to increase steal time, but there's a chance they might get one while you're stealing the cheap ones and you get that one instead.

Thanks. I hadn't dropped back for a while and there are some extremely helpful replies.

Uzael36 said:

I'm like Joncnunn, I don't believe I've ever had a tech stolen from a non-capital. This might be due to my capital always having the highest science production. Generally be a very large margin.

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Yeah, that's why the CIA is always so unattainable. It makes no sense to put a Police Station anywhere but the capital. Nobody tries to dabble into game theory at all it seems (like putting a spy where it would be least suspected).

There were multiple replies that people have tech stolen from cities other the capital. I find it frustrating because the AI seems to know better than I as to when to target something other than the capital. I would argue that the main benefit of NIA is the extra spy, much less so the theft reduction.

beetle said:

There were multiple replies that people have tech stolen from cities other the capital. I find it frustrating because the AI seems to know better than I as to when to target something other than the capital. I would argue that the main benefit of NIA is the extra spy, much less so the theft reduction.

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I've run experiments with mods, the AI really doesn't know anything about things slowing down tech acquisition rate (such as Constable, Police Station, etc.)

What is does go by is using population as a very good guess as to which city is likely to have the quickest rate. (This is also why the percentage reductions are so low in base game.)
It may also have a plus factor for city next to a mountain.

Have ongoing cargo ships (or caravans if inland) run to your capital and your capital will have so much more population compared to any other city that it's going to be the only city the AI considers.

However if you both go Liberty and don't run food to your capital, then the RNG factor is likely to on occasion send it elsewhere as another city will be close enough in population to consider.