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Last updated: 23.05.06.
First off, a short introduction. This post is mostly aimed at people who are new to Civilization IV, but it should also be of some use to the more experienced players. There is a collection of links to various other useful resources, and an advanced gameplay section which has some in-depth explanations of the game. This is a work in progress, of course, so feel free to suggest what I should add/answer. Now let’s cover the basics.
The Basics
What is this game?
You may be asking yourself this question if you heard about Civ4 and are now thinking of buying it. To put it briefly, Civ4 is a turn-based strategy game where you, as the name implies, control a civilization, starting with a group of settlers in the ancient times, and up through to the modern age with spaceflight, research laboratories and stealth bombers. “Turn-based” means that Civ4 is played in turns, like many well-known boardgames, such as chess. On your turn, you do everything that you want to do, you end your turn, and then the other civilizations do their thing.
The goal of the game is to make your civilization reign supreme through one of several victory conditions, such as conquering all other civilizations, being the first to launch a spaceship, or winning an election in the United Nations naming you the supreme leader.
Who is behind this game?
Civ4 is developed by Firaxis Games and published by 2K Games, a subsidiary of Take-Two Interactive Software. You may know 2K, the game’s publisher, by such titles as The Elder Scrolls IV: Oblivion, Call of Cthulhu: Dark Corners of the Earth, Prey or Serious Sam II.
The lead designer of Civ4 is Soren Johnson.
Is there a demo?
Yes! The demo can be downloaded right here.
System requirements and technical stuff
The official system requirements for Civ4 are:
Minimum:
1.2 GHz Intel Pentium IV or AMD Athlon processor, or equivalent;
256 MB RAM;
a CD-ROM drive (note: a DVD-ROM drive is required for the DVD version, sold in Europe);
a 64 MB video card with support of hardware T&L (GeForce 2/Radeon 7500 or better);
DirectX7-compatible sound card;
1.7 GB of hard drive space
Recommended:
1.8 GHz Intel Pentium IV or AMD Athlon processor, or equivalent;
512 MB RAM;
a CD-ROM drive (note: a DVD-ROM drive is required for the DVD version, sold in Europe);
a 128 MB video card with hardware DirectX 8 support (which means pixel and vertex shader support);
DirectX7-compatible sound card;
1.7 GB of hard drive space
What does this really mean? If you have a computer that meets the minimum system requirements, you should be able to comfortably play standard-sized and smaller maps, but in the late-game, you may have to wait a bit between turns. Also, if your PC is like the one listed for minimum requirements, playing the largest maps would probably not be comfortable for you.
If you have a computer that meets the recommended requirements, you should be able to play any built-in map sizes without problems. Personally, I am running Civ4 on a computer with 512 MB RAM, but I am able to comfortably run the game while also having a web browser or another application in the background, and switch back and forth.
What is that T&L thingie? Is my video card supported?
T&L is Transform and Lighting, a feature of video cards that Civ4 requires support for on the hardware level. All stand-alone video cards released in the last several years have T&L support. GeForce 2, the minimum required video card, was released in spring 2000.
Please note that, unfortunately, most integrated video cards still do not have support for T&L – this is mostly a problem for laptop users, because laptops are frequently equipped with integrated video cards.
To find out if your video card is supported, check this forum thread. You will find in there a comprehensive listing of video cards, and whether they can be expected to run Civ4.
I have crashes with Civ4, or other technical problems
First of all, you should install the latest patch for Civ4, which is 1.61 and is available for download from our site.
You should also check out this forum thread, which contains tips about the most frequently encountered problems and several links to solutions.
If you can not find any solution for your problems, feel free to post in our Civ4 Help forum. Try to include as much information as possible about the problem you’re experiencing, and do state your computer’s specifications.
(Relatively) simple gameplay-related questions and issues
I just got Civ4, and am feeling somewhat overwhelmed. How do I learn the game?
Civ4 is a pretty complex game, and it can be a bit intimidating first, when you don’t understand most of what’s going on. However, Civ4 doesn’t require full understanding to play – just get used to the thought that your first few games will have aspects confusing to you, and you will pick up many concepts from just the playing experience, and the interface tips.
If you haven’t done so, read the Civ4 manual. You don’t have to go through it all, but the Basic Rules section is a recommended initial read – it should give you enough understanding for your first few games. When you’re feeling comfortable with the basic concepts, take a stab at the Advanced Rules section. Don’t hesitate to consult the manual as you play. Also, don’t forget the Civilopedia – it can be accessed by pressing F12 during the game, or clicking its help icon in the upper right corner of the Civ4 screen. The Civilopedia contains information on many game concepts, similar to the manual, and it’s particularly useful to look up the abilities and effects of units, buildings and technologies.
Play your first few games at the lower difficulty levels – Settler or Chieftain. On these levels, you have significant bonuses over the computer players, so you should not be falling behind much even if you do the wrong things. Also, these first two levels are more forgiving of mistakes and have reduced enemy aggression.
How do I deal with the Barbarians?
The Barbarians can be a pesky bunch t deal with. Usually, you will first see them come towards you with a few warriors and archers, but later, they will throw the occasional Axeman into your lands. The Barbarians only appear in territory covered by the fog of war, so they are usually a short-term concern – once the entire landmass is covered by cultural borders of your civ and the others, the Barbarians are gone.
The Barbarians force you, early on, to have some military, which is inevitable, but that is also good for you. Early on, a couple of Archers will do – one Archer is certainly able to defend a city vs. Barbarian archers or Warriors, and you could use another for chasing Barbarian warriors around, or covering another city.
Probably the biggest advantage for you is that Barbarians are dumb. Most of the time, they will attack your unit, if they can do so, even if the odds are suicidal for them. Therefore, one of the best ways to deal with the Barbarians is to take an Archer and put him on a hill somewhere near where the Barbarians are coming from. Passing Barbarians are very likely to attack the Archer and lose. In fact, Barbarians are a good way to get you some promoted units.
If you see a Barbarian city pop up, you should expect a bit more Barbarian activity coming from that direction. The city might be a nice target for you to take later in the game, for keeping it or razing it. Your combat with Barbarians is also partially affected by your chosen difficulty level, as most difficulty levels, even up to the middle ones, provide slight combat bonuses vs. barbarians.
How long does / should a game of Civ4 take?
There is no right answer to this question. First, there are four game speeds available – Quick, Normal, Epic and Marathon. On Epic, for example, everything is 50% more expensive than on Normal (takes 50% more time to build, research, etc.) On Marathon, most things are twice as expensive as Epic. So which game speed you pick impacts the speed greatly. Quick games can be expected to finish within 2 or 3 hours, Normal games can take 8-12 hours, and so on.
But the second, and the more important factor, is your playing style. There are players who have Normal speed games that last 6 hours, and players for whom the same games last 15 hours. Generally, new players tend to play through the game faster, but that is by no means indicative of all new players.
If you’re just starting with Civ4, however, it’s probably best for you to start playing on Normal speed. If you feel stuff takes too few turns to build and research, try the slower speeds. Note that it’s also possible to create your own, custom game speed by modifying the game’s files.
I build some cities and then I go bankrupt!
Civ4 punishes you for expanding too quickly. Every city, from the moment you found it, must be paid for – these are the so-called maintenance costs. Furthermore, every new city slightly increases the maintenance costs in all other cities. So a new city is a net loss to you. A bit later, once the city has grown and you’ve improved it some, it will start getting you income. But essentially, there is this “build-up phase” during which the city is more of a hindrance than a benefit.
Hence, if you expand too early and too quickly, you will get more undeveloped cities than your economy can support. This may seem unusual to veterans of previous Civ games in particular, but if your economy is getting too strained, you may want to build less cities.
Just how does religion work, really?
(Note that this is explained pretty thoroughly in pages 77-82 of the Civ4 manual)
Whoever is the first to discover a technology associated with a religion founds that religion. For example, the first civ to discover Meditation founds Buddhism, and the first to discover Theology founds Christianity. When a religion is founded, then one of the founding civ’s cities becomes the “holy city” for that religion.
Religions can spread to connected cities. For example, if you just founded a religion, then each city that your holy city is connected to has a chance to also gain that religion. You won’t always be satisfied by the way your religion spreads. If you want to spread it faster, you will have to build Missionaries. A Missionary can be sent to any city of yours, or a city of a civilization you have Open Borders with. There, the Missionary can attempt to spread religion. The more religions the target city already has, the less likely the Missionary to succeed.
Having a religion in your city means that you gain access to three buildings – the temple and the monastery of that religion, and later also their cathedral. Temples are very important early buildings because of their happiness boost, and monasteries boost your research. Cathedrals are expensive buildings that boost your culture very significantly.
When you adopt a state religion, you additionally gain +1 happiness and +1 culture in every city where your state religion is present. It is good for you if other civs adopt the same state religion as you, because that tends to make your relations better – someone who has your religion might well become a good long-term ally.
If you control the Holy City for a religion, you can build a shrine in it. Shrines can only be built by Great Prophets, and give you a considerable benefit – you gain gold for each city in the world where the religion is present. Controlling two or even three Holy Cities with their respective Shrines can prove to be a good source of income.
Finally, if you control the Holy City of your state religion, you gain line of sight around all cities in the world that practice this religion.
How do I make sure other civs don’t declare war on me?
Of course, you are never going to be completely safe from declarations of war. Generally, though, most other leaders will only declare war if they have a good reason for doing so and feel that they can accomplish something with this war. Here are the three most important factors that determine war declarations:
- Relations. A civ that is Furious towards you is always more likely to declare than a civ that is Pleased. You’re not entirely safe from backstabs from Pleased civs, but those aren’t frequent. If someone is Furious with you, though, you should not forget about the possibility of war.
- Military strength. If the other civ is stronger militarily than you, it’s more likely that they will declare war. Likewise, they’re less likely to declare if your military is superior. Note that evaluation of strength isn’t limited just to numbers and technology, but also includes the overall situation. For example, if you’re at war with a western neighbour, then your eastern neighbour is likely to understand that invading you from another end would be easier.
- The other leader’s personality. All the leaders in Civ4 are different. Montezuma is probably the most psychotic one – he is hard to get along with, and is very likely to declare war if he hates you. Leaders such as Gandhi and Mansa Musa prefer peace to war. Isabella often declares war against those of different religions, and so on.
Broadly speaking, the best way not to get into wars is to maintain good relations with others. That, in turn, is easiest to accomplish by converting them to your religion (or adopting theirs). Wars with civilizations that share your religion can also happen, but they are not very frequent, and generally religion is the single biggest boosting factor to relations.
What does it mean when I trade away a resource?
When you trade away a resource, then the other civilization gets the benefits associated with it. Usually it’s extra happiness (Wine, Gold, Gems, Incense, etc.), extra health (Pigs, Cows, Sheep, Clams, etc.) or the ability to build some units (Copper, Iron, Horses, etc.). If you have more than one source of a resource, you can trade the extra ones away and still retain the benefits yourself. Note that the game doesn’t prevent you from trading away your only resource. For example, you can sell your only Iron resource, but you will not be able to build any Swordsmen, then.
In the diplomacy trading screen, there’s a number in brackets next to each resource. It indicates how many of those resources you have. If the number is 1, you’ll lose the benefit if you sell the resource. When an AI civ asks you for a deal, you see something like Horses (1 of 2). That means that the civ asks you for one source of Horses (it’s only possible to ask for one source), but you have two available – so you can trade away.
Don’t forget that Ivory is a special resource – it provides extra happiness, but also allows you to build War Elephants, which are very powerful early game units. Be careful when selling Ivory to other civilizations.
Do civilizations that don’t have Democracy get the happiness hit if I switch to Emancipation?
Yes, everyone gets hit, which, in fact, is the idea behind the implementation of Emancipation.
Are the power plants any different?
Not really, they have the same effect. Coal plants give an extra health penalty in the city, but waiting for Hydro Plants is usually not the better choice. Note that you can build The Three Gorges Dam, available with Plastics, to provide power to all cities on the continent without the need for power plants.
Can I control which city becomes the Holy City when I found a religion?
No. The Holy City is chosen randomly, so you have no control over it. Well, actually, it’s not entirely random, but it’s not controllable.
More advanced gameplay questions and answers
So, just how DOES the game determine the Holy City?
Here is the code that determines the selection of the Holy City:
How exactly does city flipping work?
On the very basic level, the more culture you have in the tile of the enemy city itself and the tiles adjacent to it, the more likely a flip is. The presence of the other civ’s state religion reduces the chance, the presence of your state religion increases the chance. For every city, there’s a number of units that would be enough to prevent the city from flipping, when it’s garrisoned with those units. Unit strength matters, too, not just the number.
The city will always first have a revolt, and only then flip, when it would have had the second revolt – the second revolt turns into a flip, if you please. Note that under the default game options, a city can not flip to any of its previous owners.
Following is an in-depth discussion of the flipping algorithm, courtesy of Locutus.
What do first strikes mean? And, how does the combat system work anyway?
The Civ4 combat system is a pretty complex beast, to ensure fair results. The full explanation is too big to post here, but you can read it in the first post of this thread. Please note that, due to the actual complexity of the system, the description is quite heavy on math, particularly the part that deals with calculating combat odds. Also note that this description might not be entirely up-to-date with respect to the 1.61 patch, as there’s been a tweak introduced in the patch, but the description remains quite precise overall.
What determines a Missionary’s chance for success?
The more religions already present in a city, the less likely the missionary is to succeed in spreading a new one. Precisely, the chance to spread religion is:
Chance = t + ((TR - r) * (100-t) / TR) , where:
t – team number. 40 if the city belongs to your team, 20 if not
TR – total religions in the game. That’s 7 unless modded.
r – religions present in the city
Hence, if you’re trying to spread religion to a city of your own that has no religions, you get 40 + 7 * 60 / 7 = 100% chance, and will always succeed. However, spreading a religion into a rival city with 5 religions already in it, that’s 20 + (2 * 80 / 7) = approx. 43% success.
Civ 4 Modding
So what are the basics behind Civ4 modding, what can and can’t you do with it?
Civ4 is a very moddable game. There are three levels of modding in Civ4, so to speak, each next level allowing you to do more, but also requiring more skills. Here you go:
1. XML files. Civ4 stores a lot of data in XML files that you can find in the Assets\XML subfolder in the Civ4 folder. Changing the XML files only requires you to have a text editor, such as Notepad in MS Windows. My personal editor of choice is EditPlus, when working on Windows, but you can use whatever you please.
By changing XML files, you can add more civilizations and leaders to the game, change the costs of technologies, strength of units, the diplomatic relation modifiers, default city names, add more promotions, change the tech tree or other things. However, XML is limited in its ability to (roughly speaking) what is already in the game. For example, you can easily add a City Raider IV promotion that would increase city attack even further. But, you can’t add a promotion that would let your units paradrop, because no such thing is in the game – while increased city attack is in. That’s a pretty rough explanation. In fact, the limiting factor obviously is which XML elements are used by Civ4. You can’t add new ones without using the SDK, as the game would have no idea what to do there.
This is not to say that you can’t do interesting stuff with XML. For example, you can add units that are only possible to build under a certain religion, or add building requirements for units, such as requiring Factories to be in place for Tanks and aircraft to be built.
2. Python. Python is a programming language that Civ4 uses for much of its interface and parts of the game itself. Through Python, you can change, for example, the advisor screens, and it can also be used as a (very powerful) scripting language. The Civ4 scenarios and the map scripts use Python, so that should give you an idea about what you can do.
With Python, you can implement quite a few cool ideas. Want enemy resistance units to pop up if you capture a city that has a different state religion to your own? No problem. Designing a scenario and you want to simulate Russian Winter by making terrain hard to pass? Python can do that too. In fact, you can even hack around and make things such as entirely new civ traits, though an implementation through SDK would probably be cleaner.
3. The SDK. Basically, this is the source code of the Civ4 DLL file. It’s the most powerful tool a modder can have, and the limits to what you can do with the SDK are, in fact, your skills and imagination. Radical ideas can be implemented that change the basics of the game – real stacked combat, a sophisticated espionage and unconventional warfare system, anything. You can even do total conversion mods – that is, turn Civ4 into something else. A remake of Alpha Centauri maybe, or maybe a glorified chess game. Really, the limits are few.
The SDK also includes the source code of the Civ4 AI, so you could play around with it to create powerful AI enhancements.
The downside is, of course, that the SDK is hard to use. It’s written in C++, so unless you are a programmer, you can’t really do much with it. Python is easy enough to learn so that you can do at least basic stuff with it, but if you have never programmed before, then you will need to spend quite a while learning before you can even begin doing something with the SDK.
How do I learn Python?
Python is a relatively simple programming language. If you have never done any programming at all, it won’t be too trivial to pick up, but you should still be able to pick it up reasonably fast. Check out the online Python documentation, particularly the Beginner’s guide.
As far as Python in Civ4 goes, Jon Shafer (aka Trip) from Firaxis has written an introduction guide to Python in Civ4. There you can read about the basics of the Python language, and also the basics of how Civ4 handles Python and how you can use it to interact with the game.
Civ4 links
Here go some links to useful Civ4 threads, resources or mods…
Vel’s strategy thread, an excellent read
A Civ4 map script reference by Sirian, the Civ4 map designer
The Modiki, a wiki-based modding resource for Civ4
Civ4 downloads from 2K, including the latest patch and the SDK
How to get the SDK to work
Dale’s combat mod. Full stack-on-stack combat and field bombardment
A World War I scenario by Firaxis
First off, a short introduction. This post is mostly aimed at people who are new to Civilization IV, but it should also be of some use to the more experienced players. There is a collection of links to various other useful resources, and an advanced gameplay section which has some in-depth explanations of the game. This is a work in progress, of course, so feel free to suggest what I should add/answer. Now let’s cover the basics.
The Basics
What is this game?
You may be asking yourself this question if you heard about Civ4 and are now thinking of buying it. To put it briefly, Civ4 is a turn-based strategy game where you, as the name implies, control a civilization, starting with a group of settlers in the ancient times, and up through to the modern age with spaceflight, research laboratories and stealth bombers. “Turn-based” means that Civ4 is played in turns, like many well-known boardgames, such as chess. On your turn, you do everything that you want to do, you end your turn, and then the other civilizations do their thing.
The goal of the game is to make your civilization reign supreme through one of several victory conditions, such as conquering all other civilizations, being the first to launch a spaceship, or winning an election in the United Nations naming you the supreme leader.
Who is behind this game?
Civ4 is developed by Firaxis Games and published by 2K Games, a subsidiary of Take-Two Interactive Software. You may know 2K, the game’s publisher, by such titles as The Elder Scrolls IV: Oblivion, Call of Cthulhu: Dark Corners of the Earth, Prey or Serious Sam II.
The lead designer of Civ4 is Soren Johnson.
Is there a demo?
Yes! The demo can be downloaded right here.
System requirements and technical stuff
The official system requirements for Civ4 are:
Minimum:
1.2 GHz Intel Pentium IV or AMD Athlon processor, or equivalent;
256 MB RAM;
a CD-ROM drive (note: a DVD-ROM drive is required for the DVD version, sold in Europe);
a 64 MB video card with support of hardware T&L (GeForce 2/Radeon 7500 or better);
DirectX7-compatible sound card;
1.7 GB of hard drive space
Recommended:
1.8 GHz Intel Pentium IV or AMD Athlon processor, or equivalent;
512 MB RAM;
a CD-ROM drive (note: a DVD-ROM drive is required for the DVD version, sold in Europe);
a 128 MB video card with hardware DirectX 8 support (which means pixel and vertex shader support);
DirectX7-compatible sound card;
1.7 GB of hard drive space
What does this really mean? If you have a computer that meets the minimum system requirements, you should be able to comfortably play standard-sized and smaller maps, but in the late-game, you may have to wait a bit between turns. Also, if your PC is like the one listed for minimum requirements, playing the largest maps would probably not be comfortable for you.
If you have a computer that meets the recommended requirements, you should be able to play any built-in map sizes without problems. Personally, I am running Civ4 on a computer with 512 MB RAM, but I am able to comfortably run the game while also having a web browser or another application in the background, and switch back and forth.
What is that T&L thingie? Is my video card supported?
T&L is Transform and Lighting, a feature of video cards that Civ4 requires support for on the hardware level. All stand-alone video cards released in the last several years have T&L support. GeForce 2, the minimum required video card, was released in spring 2000.
Please note that, unfortunately, most integrated video cards still do not have support for T&L – this is mostly a problem for laptop users, because laptops are frequently equipped with integrated video cards.
To find out if your video card is supported, check this forum thread. You will find in there a comprehensive listing of video cards, and whether they can be expected to run Civ4.
I have crashes with Civ4, or other technical problems
First of all, you should install the latest patch for Civ4, which is 1.61 and is available for download from our site.
You should also check out this forum thread, which contains tips about the most frequently encountered problems and several links to solutions.
If you can not find any solution for your problems, feel free to post in our Civ4 Help forum. Try to include as much information as possible about the problem you’re experiencing, and do state your computer’s specifications.
(Relatively) simple gameplay-related questions and issues
I just got Civ4, and am feeling somewhat overwhelmed. How do I learn the game?
Civ4 is a pretty complex game, and it can be a bit intimidating first, when you don’t understand most of what’s going on. However, Civ4 doesn’t require full understanding to play – just get used to the thought that your first few games will have aspects confusing to you, and you will pick up many concepts from just the playing experience, and the interface tips.
If you haven’t done so, read the Civ4 manual. You don’t have to go through it all, but the Basic Rules section is a recommended initial read – it should give you enough understanding for your first few games. When you’re feeling comfortable with the basic concepts, take a stab at the Advanced Rules section. Don’t hesitate to consult the manual as you play. Also, don’t forget the Civilopedia – it can be accessed by pressing F12 during the game, or clicking its help icon in the upper right corner of the Civ4 screen. The Civilopedia contains information on many game concepts, similar to the manual, and it’s particularly useful to look up the abilities and effects of units, buildings and technologies.
Play your first few games at the lower difficulty levels – Settler or Chieftain. On these levels, you have significant bonuses over the computer players, so you should not be falling behind much even if you do the wrong things. Also, these first two levels are more forgiving of mistakes and have reduced enemy aggression.
How do I deal with the Barbarians?
The Barbarians can be a pesky bunch t deal with. Usually, you will first see them come towards you with a few warriors and archers, but later, they will throw the occasional Axeman into your lands. The Barbarians only appear in territory covered by the fog of war, so they are usually a short-term concern – once the entire landmass is covered by cultural borders of your civ and the others, the Barbarians are gone.
The Barbarians force you, early on, to have some military, which is inevitable, but that is also good for you. Early on, a couple of Archers will do – one Archer is certainly able to defend a city vs. Barbarian archers or Warriors, and you could use another for chasing Barbarian warriors around, or covering another city.
Probably the biggest advantage for you is that Barbarians are dumb. Most of the time, they will attack your unit, if they can do so, even if the odds are suicidal for them. Therefore, one of the best ways to deal with the Barbarians is to take an Archer and put him on a hill somewhere near where the Barbarians are coming from. Passing Barbarians are very likely to attack the Archer and lose. In fact, Barbarians are a good way to get you some promoted units.
If you see a Barbarian city pop up, you should expect a bit more Barbarian activity coming from that direction. The city might be a nice target for you to take later in the game, for keeping it or razing it. Your combat with Barbarians is also partially affected by your chosen difficulty level, as most difficulty levels, even up to the middle ones, provide slight combat bonuses vs. barbarians.
How long does / should a game of Civ4 take?
There is no right answer to this question. First, there are four game speeds available – Quick, Normal, Epic and Marathon. On Epic, for example, everything is 50% more expensive than on Normal (takes 50% more time to build, research, etc.) On Marathon, most things are twice as expensive as Epic. So which game speed you pick impacts the speed greatly. Quick games can be expected to finish within 2 or 3 hours, Normal games can take 8-12 hours, and so on.
But the second, and the more important factor, is your playing style. There are players who have Normal speed games that last 6 hours, and players for whom the same games last 15 hours. Generally, new players tend to play through the game faster, but that is by no means indicative of all new players.
If you’re just starting with Civ4, however, it’s probably best for you to start playing on Normal speed. If you feel stuff takes too few turns to build and research, try the slower speeds. Note that it’s also possible to create your own, custom game speed by modifying the game’s files.
I build some cities and then I go bankrupt!
Civ4 punishes you for expanding too quickly. Every city, from the moment you found it, must be paid for – these are the so-called maintenance costs. Furthermore, every new city slightly increases the maintenance costs in all other cities. So a new city is a net loss to you. A bit later, once the city has grown and you’ve improved it some, it will start getting you income. But essentially, there is this “build-up phase” during which the city is more of a hindrance than a benefit.
Hence, if you expand too early and too quickly, you will get more undeveloped cities than your economy can support. This may seem unusual to veterans of previous Civ games in particular, but if your economy is getting too strained, you may want to build less cities.
Just how does religion work, really?
(Note that this is explained pretty thoroughly in pages 77-82 of the Civ4 manual)
Whoever is the first to discover a technology associated with a religion founds that religion. For example, the first civ to discover Meditation founds Buddhism, and the first to discover Theology founds Christianity. When a religion is founded, then one of the founding civ’s cities becomes the “holy city” for that religion.
Religions can spread to connected cities. For example, if you just founded a religion, then each city that your holy city is connected to has a chance to also gain that religion. You won’t always be satisfied by the way your religion spreads. If you want to spread it faster, you will have to build Missionaries. A Missionary can be sent to any city of yours, or a city of a civilization you have Open Borders with. There, the Missionary can attempt to spread religion. The more religions the target city already has, the less likely the Missionary to succeed.
Having a religion in your city means that you gain access to three buildings – the temple and the monastery of that religion, and later also their cathedral. Temples are very important early buildings because of their happiness boost, and monasteries boost your research. Cathedrals are expensive buildings that boost your culture very significantly.
When you adopt a state religion, you additionally gain +1 happiness and +1 culture in every city where your state religion is present. It is good for you if other civs adopt the same state religion as you, because that tends to make your relations better – someone who has your religion might well become a good long-term ally.
If you control the Holy City for a religion, you can build a shrine in it. Shrines can only be built by Great Prophets, and give you a considerable benefit – you gain gold for each city in the world where the religion is present. Controlling two or even three Holy Cities with their respective Shrines can prove to be a good source of income.
Finally, if you control the Holy City of your state religion, you gain line of sight around all cities in the world that practice this religion.
How do I make sure other civs don’t declare war on me?
Of course, you are never going to be completely safe from declarations of war. Generally, though, most other leaders will only declare war if they have a good reason for doing so and feel that they can accomplish something with this war. Here are the three most important factors that determine war declarations:
- Relations. A civ that is Furious towards you is always more likely to declare than a civ that is Pleased. You’re not entirely safe from backstabs from Pleased civs, but those aren’t frequent. If someone is Furious with you, though, you should not forget about the possibility of war.
- Military strength. If the other civ is stronger militarily than you, it’s more likely that they will declare war. Likewise, they’re less likely to declare if your military is superior. Note that evaluation of strength isn’t limited just to numbers and technology, but also includes the overall situation. For example, if you’re at war with a western neighbour, then your eastern neighbour is likely to understand that invading you from another end would be easier.
- The other leader’s personality. All the leaders in Civ4 are different. Montezuma is probably the most psychotic one – he is hard to get along with, and is very likely to declare war if he hates you. Leaders such as Gandhi and Mansa Musa prefer peace to war. Isabella often declares war against those of different religions, and so on.
Broadly speaking, the best way not to get into wars is to maintain good relations with others. That, in turn, is easiest to accomplish by converting them to your religion (or adopting theirs). Wars with civilizations that share your religion can also happen, but they are not very frequent, and generally religion is the single biggest boosting factor to relations.
What does it mean when I trade away a resource?
When you trade away a resource, then the other civilization gets the benefits associated with it. Usually it’s extra happiness (Wine, Gold, Gems, Incense, etc.), extra health (Pigs, Cows, Sheep, Clams, etc.) or the ability to build some units (Copper, Iron, Horses, etc.). If you have more than one source of a resource, you can trade the extra ones away and still retain the benefits yourself. Note that the game doesn’t prevent you from trading away your only resource. For example, you can sell your only Iron resource, but you will not be able to build any Swordsmen, then.
In the diplomacy trading screen, there’s a number in brackets next to each resource. It indicates how many of those resources you have. If the number is 1, you’ll lose the benefit if you sell the resource. When an AI civ asks you for a deal, you see something like Horses (1 of 2). That means that the civ asks you for one source of Horses (it’s only possible to ask for one source), but you have two available – so you can trade away.
Don’t forget that Ivory is a special resource – it provides extra happiness, but also allows you to build War Elephants, which are very powerful early game units. Be careful when selling Ivory to other civilizations.
Do civilizations that don’t have Democracy get the happiness hit if I switch to Emancipation?
Yes, everyone gets hit, which, in fact, is the idea behind the implementation of Emancipation.
Are the power plants any different?
Not really, they have the same effect. Coal plants give an extra health penalty in the city, but waiting for Hydro Plants is usually not the better choice. Note that you can build The Three Gorges Dam, available with Plastics, to provide power to all cities on the continent without the need for power plants.
Can I control which city becomes the Holy City when I found a religion?
No. The Holy City is chosen randomly, so you have no control over it. Well, actually, it’s not entirely random, but it’s not controllable.
More advanced gameplay questions and answers
So, just how DOES the game determine the Holy City?
Here is the code that determines the selection of the Holy City:
Code:
iBestValue = 0;
pBestCity = NULL;
for (pLoopCity = firstCity(&iLoop); pLoopCity != NULL; pLoopCity = nextCity(&iLoop))
{
if (!bStarting || !(pLoopCity->isHolyCity()))
{
iValue = 10;
iValue += pLoopCity->getPopulation();
iValue += GC.getGameINLINE().getSorenRandNum(GC.getDefineINT("FOUND_RELIGION_CITY_RAND"), "Found Religion");
iValue /= (pLoopCity->getReligionCount() + 1);
if (pLoopCity->isCapital())
{
iValue /= 8;
}
iValue = max(1, iValue);
if (iValue > iBestValue)
{
iBestValue = iValue;
pBestCity = pLoopCity;
}
}
}
On the very basic level, the more culture you have in the tile of the enemy city itself and the tiles adjacent to it, the more likely a flip is. The presence of the other civ’s state religion reduces the chance, the presence of your state religion increases the chance. For every city, there’s a number of units that would be enough to prevent the city from flipping, when it’s garrisoned with those units. Unit strength matters, too, not just the number.
The city will always first have a revolt, and only then flip, when it would have had the second revolt – the second revolt turns into a flip, if you please. Note that under the default game options, a city can not flip to any of its previous owners.
Following is an in-depth discussion of the flipping algorithm, courtesy of Locutus.
Algorithm
At the start of every turn, the game will look at every city in the game that's not occupied and of which the player with the strongest cultural presence (the 'attacker') is not the same as the physical owner (the 'defender'). For each of these cities, there is a (by default) 10% chance that the game will try to revolt it. If this happens and the city is Barbarian, the city flip immediately takes place. If the city is not Barbarian, it compares the culture strength of the attacker (see below) with the sum of the culture garrison (see below) of all units in the city (whether they belong to the defender or someone else). If the total culture garrison is higher than the culture strength of the attacker, the city will never revolt. If OTOH the cultural strength of the attacker is higher, then the bigger the difference between the total culture garrison and the culture strength, the bigger the chance the city will revolt (to be precise, the chance is culture garrison divided by culture strength). Of course, as mentioned, the second time a city revolts it flips.
The culture garrison (CG) is a property every unit has. For non-combat, air and naval units this is 0, for land combat units it depends on how powerful the unit is. Warrior and Quechua have the lowest value of at 3, Modern Armor and Mechanized Infantry have the highest at 16. As mentioned, the sum of these values of all units (regardless of their owner) in a city determines if a city can revolt and what the chance of it happening is. Note though that if the defender and attacker are at war with each other, the defender gets a 100% bonus on the culture garrison.
The culture strength that the attacker has in a disputed city is calculated using a rather complicated formula. It's influenced by the highest size a city ever had, the amount of plots bordering the city that the attacker owns, the average era (ancient, medieval, modern) of all surviving players, the culture value of the attacker has in the plot compared to the defender, and if the state religion(s) of both the attacker and the physical owner is/are present in the city. Obviously, the more of everything, the stronger the culture strength.
Strength Formula
The exact culture strength formula is the following:
City Strength = 1 + ((1 + Highest Size + (Owned Plots * Era Index)) * Culture Percent) / 100
where:
- Highest Size is the highest size the city ever had;
- Owned Plots is the number of plots neighbouring the city that the attacker owns;
- Era Index is the average value of the era indices of all surviving players, with 1 being the lowest (so ancient = 1, future = 7);
- Culture Percent is roughly how much culture the defender has compared to the attacker, as a percentage of the attacker's value (e.g. if the attacker has 60% culture, then defender has 40%, which is a third less (20/60 = 1/3), so Culture Percent becomes roughly 33).
Finally, the presence of the attacker's state religion in the city doubles the strength, the presence of the defender's state religion halves it.
Example 1
Let's say a city is size 8 (and was never larger than that), 4 plots surrounding it belong to the attacker, the average era is medieval (index 3) and the attacker has 67% culture, the defender 33% (so the attacker has 50% more culture). Now the culture strength can be calculated:
City Strength = 1 + ((1 + 8 + 4*3) * 50) / 100 = 1 + (21 * 50) / 100 = 1 + (1050 / 100) = 11.5
That means 2 medieval units at 6 CG each (e.g. Longbowmen) would keep this city safe from revolting, even if no state religion is present (or both civs have their state religion present). Let's say that at this point a culture bomb is dropped and gives the attacker 100% culture (effectively 100% more than the defender) and swallows up all neighbouring plots. All else remains unchanged. Now the situation is the following:
City Strength = 1 + ((1 + 8 + 8*3) * 100) / 100 = 1 + 33 * 100 / 100 = 34
At this point it would take 6 medieval units to defend it. If it only has two, there's a (34-2*6)/34 = 65% chance that IF the game tries to revolt the city, it will indeed revolt. That measn that on any given turn the chance that the city will revolt is 10% of 65% = 6.5%, so it should in theory take about 15 turns for the city to revolt for the first time and another 15 for it to revolt and second time and flip (assuming everything else stays the same all this time).
Example 2
Let's say a city is size 3 (and was never larger than that) with 6 surrounding plots belonging to the attacker, the average era is medieval (index 3) and the attacker has 85% culture (that means about 80% more than the defender). A situation like this may well occur if the AI founds a city in a stupid place and the human tries to get it to flip. This seems like a shoe-in for the attacker, right?
City Strength = 1 + ((1 + 3 + 6*3) * 80) / 100 = 1 + (22 * 80) / 100 = 1 + (1760 / 100) = 18.6
If the defender has 3 medieval units in this city (6 CG each), the odds that this city will revolt in any given turn are 1/10 * (18.6-3*6)/18.6 = 1/31. So despite the seemingly overwhelming odds for the attacker, it still takes in theory 31 turns before the city revolts even once, 62 turns for it to actually flip (in theory, in reality it might go faster or it might take even longer). And if the defender also has the state religion bonus, it takes twice as long: 124 turns! And if the defender adds one more unit, even a lowly Warrior, the city will even be completely impervious to flipping.
Strategy
So, what does this mean for strategy? Well, to 'cuturally attack' a Barbarian city, all you have to do is get more than 50% of your culture in the tile (or at least more than anyone else, if there are other players with cultural influence in the city as well) and wait. Taking over Barb cities is pretty easy to do, a lot easier than an AI or human city, so if you want take over a Barb city, make sure you get there first.
To attack a civilized city, make sure you own as many neighbouring tiles as possible, maximise your culture value in the city itself and also very important but perhaps not very widely known: spread your state religion there. It doubles the chance of a revolt! In case it's a close call, what can also help a bit is advancing to the highest era you can on the tech tree and either killing off primitive civs or giving them some of your more advanced techs (to increase the average era of all surviving players). More indirectly, you'll want try to lure away units from the city, as they form the main obstacle once you get your own culture rating over 60% or so. Requesting the defending civ to switch to a state religion that's not present in the city could be a big help and obviously preventing it from boosting its culture value on the plot on which the city is located (which will mostly come from the city in question, but might come from nearby cities as well) is also very helpful, if not usually something you have a great deal of control over (most you can do is keep them out of culture-friendly civics and make sure they're always at war with someone so they don't build too much).
Finally, flip any cities you want to flip as early in the game as possible, as the culture garrison values rise swiftly with time (more swiftly than era indices).
At the start of every turn, the game will look at every city in the game that's not occupied and of which the player with the strongest cultural presence (the 'attacker') is not the same as the physical owner (the 'defender'). For each of these cities, there is a (by default) 10% chance that the game will try to revolt it. If this happens and the city is Barbarian, the city flip immediately takes place. If the city is not Barbarian, it compares the culture strength of the attacker (see below) with the sum of the culture garrison (see below) of all units in the city (whether they belong to the defender or someone else). If the total culture garrison is higher than the culture strength of the attacker, the city will never revolt. If OTOH the cultural strength of the attacker is higher, then the bigger the difference between the total culture garrison and the culture strength, the bigger the chance the city will revolt (to be precise, the chance is culture garrison divided by culture strength). Of course, as mentioned, the second time a city revolts it flips.
The culture garrison (CG) is a property every unit has. For non-combat, air and naval units this is 0, for land combat units it depends on how powerful the unit is. Warrior and Quechua have the lowest value of at 3, Modern Armor and Mechanized Infantry have the highest at 16. As mentioned, the sum of these values of all units (regardless of their owner) in a city determines if a city can revolt and what the chance of it happening is. Note though that if the defender and attacker are at war with each other, the defender gets a 100% bonus on the culture garrison.
The culture strength that the attacker has in a disputed city is calculated using a rather complicated formula. It's influenced by the highest size a city ever had, the amount of plots bordering the city that the attacker owns, the average era (ancient, medieval, modern) of all surviving players, the culture value of the attacker has in the plot compared to the defender, and if the state religion(s) of both the attacker and the physical owner is/are present in the city. Obviously, the more of everything, the stronger the culture strength.
Strength Formula
The exact culture strength formula is the following:
City Strength = 1 + ((1 + Highest Size + (Owned Plots * Era Index)) * Culture Percent) / 100
where:
- Highest Size is the highest size the city ever had;
- Owned Plots is the number of plots neighbouring the city that the attacker owns;
- Era Index is the average value of the era indices of all surviving players, with 1 being the lowest (so ancient = 1, future = 7);
- Culture Percent is roughly how much culture the defender has compared to the attacker, as a percentage of the attacker's value (e.g. if the attacker has 60% culture, then defender has 40%, which is a third less (20/60 = 1/3), so Culture Percent becomes roughly 33).
Finally, the presence of the attacker's state religion in the city doubles the strength, the presence of the defender's state religion halves it.
Example 1
Let's say a city is size 8 (and was never larger than that), 4 plots surrounding it belong to the attacker, the average era is medieval (index 3) and the attacker has 67% culture, the defender 33% (so the attacker has 50% more culture). Now the culture strength can be calculated:
City Strength = 1 + ((1 + 8 + 4*3) * 50) / 100 = 1 + (21 * 50) / 100 = 1 + (1050 / 100) = 11.5
That means 2 medieval units at 6 CG each (e.g. Longbowmen) would keep this city safe from revolting, even if no state religion is present (or both civs have their state religion present). Let's say that at this point a culture bomb is dropped and gives the attacker 100% culture (effectively 100% more than the defender) and swallows up all neighbouring plots. All else remains unchanged. Now the situation is the following:
City Strength = 1 + ((1 + 8 + 8*3) * 100) / 100 = 1 + 33 * 100 / 100 = 34
At this point it would take 6 medieval units to defend it. If it only has two, there's a (34-2*6)/34 = 65% chance that IF the game tries to revolt the city, it will indeed revolt. That measn that on any given turn the chance that the city will revolt is 10% of 65% = 6.5%, so it should in theory take about 15 turns for the city to revolt for the first time and another 15 for it to revolt and second time and flip (assuming everything else stays the same all this time).
Example 2
Let's say a city is size 3 (and was never larger than that) with 6 surrounding plots belonging to the attacker, the average era is medieval (index 3) and the attacker has 85% culture (that means about 80% more than the defender). A situation like this may well occur if the AI founds a city in a stupid place and the human tries to get it to flip. This seems like a shoe-in for the attacker, right?
City Strength = 1 + ((1 + 3 + 6*3) * 80) / 100 = 1 + (22 * 80) / 100 = 1 + (1760 / 100) = 18.6
If the defender has 3 medieval units in this city (6 CG each), the odds that this city will revolt in any given turn are 1/10 * (18.6-3*6)/18.6 = 1/31. So despite the seemingly overwhelming odds for the attacker, it still takes in theory 31 turns before the city revolts even once, 62 turns for it to actually flip (in theory, in reality it might go faster or it might take even longer). And if the defender also has the state religion bonus, it takes twice as long: 124 turns! And if the defender adds one more unit, even a lowly Warrior, the city will even be completely impervious to flipping.
Strategy
So, what does this mean for strategy? Well, to 'cuturally attack' a Barbarian city, all you have to do is get more than 50% of your culture in the tile (or at least more than anyone else, if there are other players with cultural influence in the city as well) and wait. Taking over Barb cities is pretty easy to do, a lot easier than an AI or human city, so if you want take over a Barb city, make sure you get there first.
To attack a civilized city, make sure you own as many neighbouring tiles as possible, maximise your culture value in the city itself and also very important but perhaps not very widely known: spread your state religion there. It doubles the chance of a revolt! In case it's a close call, what can also help a bit is advancing to the highest era you can on the tech tree and either killing off primitive civs or giving them some of your more advanced techs (to increase the average era of all surviving players). More indirectly, you'll want try to lure away units from the city, as they form the main obstacle once you get your own culture rating over 60% or so. Requesting the defending civ to switch to a state religion that's not present in the city could be a big help and obviously preventing it from boosting its culture value on the plot on which the city is located (which will mostly come from the city in question, but might come from nearby cities as well) is also very helpful, if not usually something you have a great deal of control over (most you can do is keep them out of culture-friendly civics and make sure they're always at war with someone so they don't build too much).
Finally, flip any cities you want to flip as early in the game as possible, as the culture garrison values rise swiftly with time (more swiftly than era indices).
The Civ4 combat system is a pretty complex beast, to ensure fair results. The full explanation is too big to post here, but you can read it in the first post of this thread. Please note that, due to the actual complexity of the system, the description is quite heavy on math, particularly the part that deals with calculating combat odds. Also note that this description might not be entirely up-to-date with respect to the 1.61 patch, as there’s been a tweak introduced in the patch, but the description remains quite precise overall.
What determines a Missionary’s chance for success?
The more religions already present in a city, the less likely the missionary is to succeed in spreading a new one. Precisely, the chance to spread religion is:
Chance = t + ((TR - r) * (100-t) / TR) , where:
t – team number. 40 if the city belongs to your team, 20 if not
TR – total religions in the game. That’s 7 unless modded.
r – religions present in the city
Hence, if you’re trying to spread religion to a city of your own that has no religions, you get 40 + 7 * 60 / 7 = 100% chance, and will always succeed. However, spreading a religion into a rival city with 5 religions already in it, that’s 20 + (2 * 80 / 7) = approx. 43% success.
Civ 4 Modding
So what are the basics behind Civ4 modding, what can and can’t you do with it?
Civ4 is a very moddable game. There are three levels of modding in Civ4, so to speak, each next level allowing you to do more, but also requiring more skills. Here you go:
1. XML files. Civ4 stores a lot of data in XML files that you can find in the Assets\XML subfolder in the Civ4 folder. Changing the XML files only requires you to have a text editor, such as Notepad in MS Windows. My personal editor of choice is EditPlus, when working on Windows, but you can use whatever you please.
By changing XML files, you can add more civilizations and leaders to the game, change the costs of technologies, strength of units, the diplomatic relation modifiers, default city names, add more promotions, change the tech tree or other things. However, XML is limited in its ability to (roughly speaking) what is already in the game. For example, you can easily add a City Raider IV promotion that would increase city attack even further. But, you can’t add a promotion that would let your units paradrop, because no such thing is in the game – while increased city attack is in. That’s a pretty rough explanation. In fact, the limiting factor obviously is which XML elements are used by Civ4. You can’t add new ones without using the SDK, as the game would have no idea what to do there.
This is not to say that you can’t do interesting stuff with XML. For example, you can add units that are only possible to build under a certain religion, or add building requirements for units, such as requiring Factories to be in place for Tanks and aircraft to be built.
2. Python. Python is a programming language that Civ4 uses for much of its interface and parts of the game itself. Through Python, you can change, for example, the advisor screens, and it can also be used as a (very powerful) scripting language. The Civ4 scenarios and the map scripts use Python, so that should give you an idea about what you can do.
With Python, you can implement quite a few cool ideas. Want enemy resistance units to pop up if you capture a city that has a different state religion to your own? No problem. Designing a scenario and you want to simulate Russian Winter by making terrain hard to pass? Python can do that too. In fact, you can even hack around and make things such as entirely new civ traits, though an implementation through SDK would probably be cleaner.
3. The SDK. Basically, this is the source code of the Civ4 DLL file. It’s the most powerful tool a modder can have, and the limits to what you can do with the SDK are, in fact, your skills and imagination. Radical ideas can be implemented that change the basics of the game – real stacked combat, a sophisticated espionage and unconventional warfare system, anything. You can even do total conversion mods – that is, turn Civ4 into something else. A remake of Alpha Centauri maybe, or maybe a glorified chess game. Really, the limits are few.
The SDK also includes the source code of the Civ4 AI, so you could play around with it to create powerful AI enhancements.
The downside is, of course, that the SDK is hard to use. It’s written in C++, so unless you are a programmer, you can’t really do much with it. Python is easy enough to learn so that you can do at least basic stuff with it, but if you have never programmed before, then you will need to spend quite a while learning before you can even begin doing something with the SDK.
How do I learn Python?
Python is a relatively simple programming language. If you have never done any programming at all, it won’t be too trivial to pick up, but you should still be able to pick it up reasonably fast. Check out the online Python documentation, particularly the Beginner’s guide.
As far as Python in Civ4 goes, Jon Shafer (aka Trip) from Firaxis has written an introduction guide to Python in Civ4. There you can read about the basics of the Python language, and also the basics of how Civ4 handles Python and how you can use it to interact with the game.
Civ4 links
Here go some links to useful Civ4 threads, resources or mods…
Vel’s strategy thread, an excellent read
A Civ4 map script reference by Sirian, the Civ4 map designer
The Modiki, a wiki-based modding resource for Civ4
Civ4 downloads from 2K, including the latest patch and the SDK
How to get the SDK to work
Dale’s combat mod. Full stack-on-stack combat and field bombardment
A World War I scenario by Firaxis
). The cultural game is by no means unbalancing in Civ IV, nor is it a poor feature this time around.
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