WARNING: This guide is no longer updated. Beware factual inaccuracies and proposed strategies which may not be optimum. For something more up-to-date, look at the Brave New World guide.

Zigzagzigal's Guide to the Inca (BNW)

Note: The Incans require the Spain and Inca Double Civ Pack DLC. This guide is based around Gods and Kings mechanics and some elements are outdated in the Brave New World expansion.

The Incans are an excellent Civilization for peaceful victories, so long as you can reach mountains. Historically, the Incans achieved greatness with a vast empire spanning across much of the Andes mountains (and surprisingly high up them, too.) They're also a decent choice for moving up in difficulty level, as you can set the terrain to favour you (Highland style maps or older Earths have more hills and mountains and thus a greater advantage for you.)


Before I go into depth with this guide, here's an explanation of some terminology I'll be using throughout for the sake of newer players.

Finisher - The bonus for completing a Social Policy tree (e.g. Free Great Person for Liberty.)
Melee Units - In most contexts in Civilization 5, melee units are land units without a ranged attack. (Not just Warriors, Swordsmen, Longswordsmen, Spearmen and Pikemen)
Opener - The bonus for unlocking a Social Policy tree (e.g. +1 culture for every city for Liberty's opener)
Spotter - A unit which provides a line of sight for units with higher range than sight (such as siege units or Range-promoted archery units)
Tall Empire - A small number of cities with a high population each. Terrace Farms will help you achieve this.
Turtle - As in to "turtle up". Refers to a highly defensive state where expansion is limited. This is fine to do once you've taken all the mountains you need.
UA - Unique Ability - the unique thing a Civilization has which doesn't need to be built.
UI - Unique Improvement (also referred to as Unique Tile Improvement) - A special form of worker tile improvement that can only be built by one Civilization. Unlike unique buildings and units, it doesn't replace anything else.
UU - Unique Unit - A replacement for a normal unit that can only be built by one Civilization or provided by Militaristic City-States when allied.
Uniques - Collective name for Unique Abilities, Units, Buildings, Tile Improvements and Great People

I'm a newbie at guides and I'm by no means the best Civ 5 player around (I can put together Civ-specific strategies well, but I'm poor at more generic strategy). Corrections or better strategies would be useful.

Start Bias

The Incans are biased towards hill tiles. There's a decent chance you'll start near mountains (particularly as no other Civ has a hill start bias.) Even if you don't get mountains, hills near your capital will allow you to take advantage of Terrace Farms as soon as you can build them.

Uniques

The Incans were the first Civilization to come with a Unique Tile Improvement - the Terrace Farm. This first comes along in the Classical era but will be useful throughout the game. Their Unique Unit comes in the Ancient era.

Unique Ability: Great Andean Road

• All units moving into hill tiles only use one movement point.
  
• Hills with forest or jungle also only use one movement point for units to enter.
  
• This does not affect crossing rivers onto hill tiles.
  
• Roads and Railroads built on hill tiles have no maintenance.
  
• Roads and Railroads built on tiles without hills have half normal maintenance.

Unique Unit: Slinger (Replaces the Archer)

• Requires the Archery technology (Ancient era, 1st column, 2nd column overall)
  
• 4 strength, down from 5 (-20%)
  
• Chance to withdraw if attacked by enemy melee land units (i.e. all non-ranged land units)

Unique Tile Improvement: Terrace Farm

• Requires the Construction technology (Classical era, 1st column, 4th column overall)
  
• Can only be built on hill tiles within your territory
  
• +1 food
  
• +1 additional food with Civil Service (Medieval era, 1st column, 6th column overall) with access to fresh water
  
• +1 additional food with Fertiliser (Industrial era, 1st column, 10th column overall) with NO access to fresh water
  
• +1 food for each adjacent mountain

Victory Routes

Note these scores are a matter of personal opinion based on experiences with the Civilization. You may discover a way of utilising the Civ more effectively in unconventional ways.

Cultural: 6/10
Diplomatic: 6/10
Domination: 6/10
Scientific: 8/10

Varying bonuses can be utilised for a range of victory paths. Faster hill movement could help for Domination or lower route costs could support a City-State-bribing Diplomatic victory. If you want to use the Inca to their full potential, however, Scientific victories are best.

Like the Arabians, your trait is not your strongest asset, but rather a handy secondary feature. Unlike the Arabians, your trait is pretty decent in its own right. However, it all depends heavily on settling in hill tiles - without them, you're pratically uniqueless (if that even is a word.)

Faster hill movement


Above: Look how for the first movement point, it favours the lovely safe forested hills tile in case I run into trouble.

Few Unique Abilities will be useful right from 4000 BC, but here's one that is. Faster hill movement gets your exploring units around the map faster in the early turns as any sort of hill becomes as easy to move in as open terrain. This also ensures your hill start bias doesn't slow down exploration and might even get you into some Ancient Ruins sooner.

When those pesky Barbarians come a-calling, your focus on hills and mountains will help slow them down. Faster hill movement for yourself allows you to outpace them even before you have a road network going, which should keep your improvements much safer from pillaging.

Hill movement also helps decide promotion paths for units. Most empires have a mix of rough and open terrain - a huge bias towards rough terrain means most of your defensive units can take the respective line of promotions and be able to use that bonus in most situations.

Besides the military, your civilian units also benefit from faster hill movement. Workers can move from one tile to an adjacent hill tile and start working on a new improvement in the same turn. This may not seem like much, but hills for Terrace Farms often come in lines and (particularly in faster-speed games) this could save you a fair bit of worker time over the course of the game. Your Missionaries will also gain highly from this as with 4 movement and no slowing down for hills, you can easily convert an unfriendly city without risking losing religious strength en route.

Finally, as the game runs on, forests will slowly become less common while hills cannot be removed. In the case of the Iroquois and Celts, enemies capturing their cities can cut down their forests, messing with their Unique Abilities. If you lose a city, they can't just remove the hills you have around.

Reduced Improvement Maintenance


Above: My two cities are connected - total cost? 0.5 gold. Total revenue? 7 gold. That's a lot of profit. You'll probably see a screenshot along these lines in most other guides to the Incans. That's how satisfying this is.

Just to make you love hills more, roads are free on them. Because Civilization 5 attempts to simulate some degree of plate tectonics, hills generally occur in rows allowing for long free roads. Mountain ranges particularly are your friend (Build a road adjacent to the range, over hills, connecting multiple cities. Hang on, I think I just described the real-life Incan Empire.) These free roads lead to greater profit for your empire, which could be diverted instead to supporting science buildings or defensive units.

Even roads not on hills are cheaper, being half-price. This is important if mountains are in dispersed clusters - you need a means to connect them before filling the gap with extra cities or connecting to Harbour cities.

Here's the bad news. The Incans have a terrible Unique Unit overall. That's only fair for the very strong Terrace Farm and Great Andean Road bonuses, and it's no great loss if you don't even get around to building any. After all, the Construction technology is needed for Terrace Farms and renders these obselete.

Let's start with the downside. Slingers have the lowest base strength of any military unit in the game at 4, or 20% below normal. This means they're extra-prone to attacks - especially from enemy Archers and Chariot Archers. Hence, Slingers are actually a downgrade to Archers when matched against them.

Now for the upside. Slingers are the only unique Archery unit with a unique promotion - in this case, a chance to retreat when attacked by melee attacks. This is much alike the bonus that some sea units have, giving them a chance to avoid combat and thus take no damage. If your Slinger's in retreat, this can bring them home even faster than may otherwise be the case.

The flaws of the ability are numerous, however. Because the ability is a chance rather than a sure outcome, it's unreliable and hence you cannot base strategy easily around it. The chance to retreat is lower against relatively stronger units, as well as faster units. Worst of all, retreating is harder in rough terrain or if your Slinger's adjacent to mountains. Seeing as that's your main settling area, that's a pretty bad deal.

The promotion carries over on upgrade, but is that really an advantage? Ranged units on high health being forced to retreat might just break up your army's structure or even push your unit in range of other enemies. If you promote a Slinger all the way to a Gatling Gun, the range of 1 makes retreating problematic in addition to the fact its high strength means it could defend well anyway.

Overall, the Slinger is a good contender for worst unique unit in the game. It's unreliable, carries a downside and can actually be worse than the generic unit in a number of situations. Get Construction sooner rather than later.

Still, there may be a time and a place for Slingers. A mix of promoted Slingers and newer units (such as ex-Slinger Composite Bowmen and regular Composite Bowmen) together ensures you can arrange your army so the retreat ability is a help rather than a hinderance. The strength downside disappears on upgrade, so ex-Slinger Composite Bowmen look a little better than Slingers did.

Promotions kept on upgrade

• Withdraw Before Melee

Above: Look to the right. 5 food, 2 production and 1 gold on a single tile. And it's 1680 BC.

Mechanics

Unique Tile Improvements are a joy to have, whether good or not. They make your empire look more unique - stand out from all those others. And stand out it will, as the Incan Terrace Farm is arguably the best one of them all.

Terrace Farms work similarly to regular farms, in that they add food to a tile, and more with either Civil Service or Fertiliser depending on fresh water access. Unlike regular farms, Terrace Farms can only go on hills, hence creating a good compromise between food and production.

• Grass farm: 3 food, 4 later on
  
• Plains farm: 2 food, 3 later on, 1 production
  
• Terrace farm on a non-snow hill not adjacent to mountains: 1 food, 2 later on, 2 production

A focus on hilly areas (as you'll do anyway for your UA) would normally mean doing so at the expense of food. Terrace Farms help cover for that.

Now, hilly areas are good, but the Incans really want mountains. Every mountain adjacent to a Terrace Farm increases its food yield by 1. This can create the highest food yield tiles in the game, and hence grow your cities fast for the rest of the game. Here's an exhaustive guide to bonuses:

• Start with 2 production for the hill (unless it's snow) and 1 food for the Terrace Farm
  
• Add 1 food for every adjacent mountain
  
• Add another 1 food if it's adjacent to fresh water and you have Civil Service, or if you have Fertiliser
  
• Add 1 gold if it's adjacent to a river
  
• Add 1 food, 1 gold and 1 production if it's a desert hill and the respective city has the Petra wonder
  
• Finally, add 1 gold if it's a Golden Age and it has at least 1 gold produced a turn from other sources.

Note that you cannot build Terrace Farms on bonus yield tiles (e.g. Sheep.) This is to prevent a tile being too strong (hence giving you a very strong city only a few turns after being founded.)

The maximum potential yield on a tile is 9 food, 3 production and 3 gold, but to be realistic, 7 food, 2 production and 1 gold is likely to be the best you'll ever find.

Exploit them!


Above: World's hunger problem solved in a single city.

Having lots of food is handy to grow cities (obviously.) But don't forget every point of population adds a point of science and more with respective buildings - which you're more likely to have in your bigger cities. This explains the whole idea behind going for a science victory. To back that up, settling your cities adjacent to mountains will allow you to build Observatories in the Renaissance era, meaning your massive population could give you a crazy amount of science.

Now you know where the food's heading, it's good to know how you can make the most out of it. There are several early-game boosts to city growth, as follows:

• Tradtion Social Policy - Landed Elite (+2 food, +10% growth in capital)
  
• Tradition Finisher (Free Aquaduct and +15% growth in first 4 cities)
  
• Wonder - Temple of Artemis (+10% growth in all cities and +15% production of ranged units)
  
• Pantheon - Fertility Rites (+10% growth)
  
• Follower belief - Swords Into Plowshares (+15% growth when not at war)

More information about each individual boost will come later in their respective sections. The first two are not exclusive, so you can always pick them up no matter the game.

Stacking these bonuses will ensure you can get cities up to their full potential faster. This lets you assign specialists as soon as they become avaliable (and with Rationalism's science boost to specialists, produce lots more science.)


Above: Not even unhappiness will slow this city's relentless growth. Keep in mind this is on Marathon speed.

The path to take with culture is pretty obvious with tall cities. Tradition, Rationalism and Freedom. Between finishing Tradition and starting Rationalism, unless you have Social Policy saving enabled, you'll probably have to take at least an opener from another early tree.

Tradition - Opener

Mountains are costlier to buy with gold than other tiles, which may be a problem if you're trying to reach a hill on the other side of one for a Terrace Farm. Hence, faster border expansion can help you by saving cash from other tiles to spend on buying those mountains. The culture is a bit helpful, but not really the key feature.

Tradition - Legalism

Free culture buildings in your first four cities is handy to compensate for the fact you may be neglecting such buildings in favour of science, but that's not the reason why choosing this policy first is a good idea. It leads into more useful ones, and the sooner you have them, the more considerable your advantage.

Tradition - Landed Elite

Despite your hill starting bias, it's fairly likely your starting position lacks nearby mountains, quite possibly leaving your capital as the only major city without. More food will help even up that difference. If you're lucky and do start near mountains, you'll have an incredibly huge city by the end of the game helped along with the 10% bonus.

Tradition - Monarchy

Even without mountains, you can still build Terrace Farms in hill tiles for food. Incan cities can grow larger than any other Civ's cities. Hence, gold and reduced unhappiness is a considerable bonus for your nation, particularly in the earlier years where scraping together gold may be a problem.

Tradition - Aristocracy

While there are a couple of handy early wonders for the Incans, it's a bigger priority to get your cities growing early, hence the reason for going for Landed Elite first. Nonetheless, this is still a good bonus for getting mid-game wonders such as the Porcelain Tower. Seeing as you'll raise new cities to size 10+ pretty quickly, getting the happiness point per 10 citizens definitely comes in handy.

Tradition - Oligarchy

If you feel like keeping a few Slingers around for their retreating promotion, Oligarchy lets you hide them away in cities to avoid maintenance. More importantly, large cities have higher combat strength, and a considerable ranged attack bonus makes your cities very hard to take out.

Tradition - Finisher

Even if your culture rate is very low, you'll want to take this policy. A 15% bonus to growth is roughly equivalent to 1 extra food for every 7, letting you stretch your Terrace Farms further. Free Aquaducts help cut city maintenance costs while letting your cities grow even faster.

Liberty - Opener

When you're done with Tradition, but not yet on Rationalism, Liberty's opener allows your culture-starved cities to expand their borders if they couldn't already. Together with Tradition's opener, this helps to save cash in tile purchasing. The main reason for this policy is heading into Citizenship.

Liberty - Citizenship

The idea here is to get Terrace Farms up and running quicker, therefore allowing taller cities earlier in the game (and the considerable tech advantage that brings.)

Liberty - Meritocracy

If you still aren't in the Renaissance era by this point, taking Meritocracy is probably your best choice for 9th Social Policy. Reduced unhappiness from citizens and happiness from your extra-cheap routes will certainly come in handy in the happiness-starved midgame.

Commerce - Opener

As an alternative to opening Liberty, the Commerce opener stacks well with Monarchy in the Tradition tree to rake in plenty of gold from growing your cities. Expanding further into the Commerce tree isn't really worthwhile.

Rationalism - Opener

More science. Can't argue with that. Just be sure your fast-growing cities don't jeopardise happiness.

Rationalism - Secularism

Probably one of the best policies around for the Incans. Because your cities will be growing huge quickly, it's quite likely you'll fill all your specialist slots. This means an awful lot of science. Hence, you should nearly always pick this one up first.

Rationalism - Free Thought

Because you'll get a lot of food from Terrace Farms, one possibility is to plant Trading Posts on riverside tiles instead of Farms. Besides cash for Research Agreements, the science you now gain stacks nicely with all the research multipliers you'll likely have in your cities. The University bonus is always good.

Rationalism - Scientific Revolution

War won't be your focus, and you aren't spamming cities everywhere. Hence, signing away lots of Research Agreements won't be too hard, especially with extra cash from other policies and cash saved from cheap routes.

Rationalism - Humanism

If large cities are pulling happiness below the bar of the 15% bonus to Science, this will help. The happiness bonus to Observatories in particular is quite a sweetener to the deal, as thanks to your heavy mountain focus, you'll have one in a large proportion of your cities. Usually, you should get through the other strand of Rationalism first.

Rationalism - Sovereignity

Having many buildings will cost you a fair bit in maintenance. While cheap roads help, they may not be enough. Cash back on science buildings helps you to get more going. In most situations, this should be your last policy from Rationalism.

Rationalism - Finisher

The late game is pretty loose for technology paths. Hence, you can use free technologies to really push into some high-cost technologies for a significant head start on Spaceship building or push for a Domination victory with help from your UA.

Freedom - Opener

All those specialists you'll have in your cities will produce a healthy stream of Great People. It's only fair to boost that further. Engineers and Scientists will be useful anyway, while Artists are best off for Golden Ages and Merchants for Trade Missions for the Inca.

Freedom - Civil Society

First things first. Normal growth bonuses aren't the same as food bonuses. A 10% growth bonus for example will speed up your city growing from size X to Y by 10%, but it won't increase the maximum size the city could potentially reach.

Civil Society's bonus is different. With half the food cost for specialists, your cities will not only grow at even faster speeds but also have a higher potential limit. The sky used to be the limit, but you broke that too. An excellent first choice for Freedom.

Freedom - Democracy

By this point of the game, happiness shouldn't be the problem it used to be. Still, reducing unhappiness makes Golden Ages more frequent which gives you extra production amongst other goodies - useful in the late science player's game when the focus shifts to production.

Freedom - Constitution

Wonders aren't your main focus. Nonetheless, extra culture in an otherwise starved empire will be handy for possibly squeezing in a couple more Social Policies. Get this after Civil Society at

Freedom - Free Speech

Maintenance-free units help ensure more cash is freed up for research agreements.

Freedom - Universal Suffrage

Tall cities have high strength anyway. As you start work on a Spaceship, you'll attract enemy attention, so this helps defend. The priority of this policy depends on how likely you are to be attacked.

Freedom - Finisher

Your settled Engineers and Scientists will be worth so much more now, and extra happiness from Democracy will have its effect magnified with longer Golden Ages. Saving Great Artists until you're onto Spaceship techs is a possible strategy to ensure maximum impact of that production bonus Golden Ages bring.

The Incans by no means excel at faith generation, but it's still very much worth it to grab a religion. If you can't get one in time, don't worry. The main bonuses you're going for don't require you to be the religion's founder, so just favour the religion that has them.

Pantheon - Fertility Rites

Terrace Farms bring in so much food that you'll really see the difference a 10% growth bonus makes sooner rather than later. As a Pantheon, it'll spread to all the cities you found until you found a religion, so early expansion brings this to maximum early-game potential.

Pantheon - Messenger of the Gods

A very respectable choice if you can't get Fertility Rites. Cheap routes means this'll come into effect quickly (as there's no need to hold back on road-building for financial reasons.) More science is always good.

Pantheon - Goddess of Love

In the early game, you have the problem of ensuring you're getting good city spots while still building tall. This can make happiness quite a concern. A little extra happiness from your larger cities should help to keep expansion rolling.

Founder - Tithe

A consistently effective choice. Your very large cities will be a safe source of revenue for buying tiles, buildings or Research Agreements. Notably, this is the only Founder belief based on population which doesn't require foreign cities to operate - handy as your likely weak faith generation won't be very good at doing that.

Founder - Interfaith Dialogue

Also a decent choice. If you're up against strong religious players, this is probably better than Tithe, as your own cities will probably be converted to their religion. Interfaith Dialogue is more effective on larger cities, and yours are massive.

Follower - Swords into Plowshares

The obvious choice, capitalising on high food production.

Follower - Religious Community

Sacrificing potential Mines for Terrace Farms may hurt your production. Luckily, tall cities gain the most from this belief, putting your cities back on par with other places and putting you well on the way for the eventual Spaceship.

Follower - Feed the World

Missing out on Swords into Plowshares? Feed the World will nudge your food production up that little bit higher, though the need to build Shrines and Temples is a problem.

Follower - Guruship

Not nearly as strong as Swords into Plowshares or Religious Community but more useful than many alternatives, Guruship takes advantage of the fact large cities tend to have specialists present, and gives you a little production which is useful no matter your path.

Enhancer - Itinerant Preachers

If you're taking Tithe, you want your religion to have a presence in as many cities as possible, even if it's not dominant. Otherwise, this could help back up your religious pressure between cities, keeping your own cities in your own faith.

Enhancer - Defender of the Faith

If hill-settling and high-strength cities weren't enough, add a 25% bonus on top. It'll be hard for those militaristic enemies to get at you now.

Despite all the hills around, the Incans don't particularly excel at production and hence won't get many wonders built as tall empires go. Nonetheless, there's plenty to choose from...

Ancient Era - Great Library

Gives a huge early-game boost to science. Seeing as that's the path you're likely to be heading, it's a good idea if you can build it fast enough.

Ancient Era - Hanging Gardens

Because you should focusing on stacked growth bonuses already to make the most of Terrace Farms, it makes the Hanging Gardens go further, too. Preferably, this should go in your capital due to Tradition policies that focus on it and the fact your capital may not start near mountains for Terrace Farms' full potentials.

Ancient Era - Temple of Artemis

Faster ranged unit production could be used to churn out Slingers, but the main reason for getting this is the growth rate bonus. It's not a popular wonder to pick up, but it's cheap, meaning you're safe to put it off a little (just not too much.)

Classical Era - Great Wall

You already have a speed advantage on your own land with hills. But why not bring that further? Now, enemy mounted units will be impratically slow. This is the only wonder that obseletes, though, and there are other similar-era wonders that are more useful.

Classical Era - Petra

Desert hill tiles gain the most out of Petra, gaining a base yield of 1 food, 3 production and 1 gold. Desert hills near mountains become extremely good tiles. Know your map early to find a good Petra city, as in Incan hands, it could be one of the game's most powerful cities.

Medieval Era - Angkor Wat

Mountain tiles are expensive to buy (and you often will have to purchase them to get hills on the other side for Terrace Farms.) Angkor Wat makes it more affordable, and stacks nicely with the Tradition Social Policy tree opener.

Medieval Era - Machu Picchu

While normally a wonder for wide-building players, the high profits from trade routes you'll make is a good incentive to bring that further.

Medieval Era - Notre Dame

The mid-game often suffers from happiness problems. Get this, and it's a problem annihilated.

Renaissance Era - Forbidden Palace

As most of your unhappiness will be from population, a 10% reduction is pretty significant. After this point, you probably will have very little trouble with happiness for the rest of the game.

Renaissance Era - Leaning Tower of Pisa

Having lots of specialists will generate Great People rapidly. Might as well add to this! The free Great Person can mean lots more production or science for a city (Academies near an Observatory city are very powerful)

Renaissance Era - Porcelain Tower

Signing Research Agreements is easy when you've been playing peacefully, not expanding wide too much and have cash from cheap roads to afford them. And even if you still can't make them, the free Great Scientist will come in handy.

Industrial Era - Big Ben

If you can't get anyone interested in Research Agreements, consider pouring your cash into buying the science buildings you need instead. Big Ben will assist with this aim.

Modern Era - Statue of Liberty

With so many specialists from a high population, you'll rake in the production. A must-have wonder on the way to building the Spaceship.

Atomic Era - Great Firewall

Tall cities have massive spy potential. Find your biggest city, and build the Great Firewall in it to stop enemies seizing your technology advantage.

Information Era - Hubble Telescope

While most of your cities will have great growth, they may not necessarilly have exceptional production due to a focus on Terrace Farms rather than Mines. The exception to the rule is probably your capital, which is likely to lack mountains and thus the hills in the area will probably be used for production rather than food. Build the Hubble Telescope there, and the rest of your cities will gain in that final push for victory.

While an easy nation to play, it's nonetheless quite possible to get things wrong as the Incans.

Huge road detours to save cash leave you vulnerable!

It might be tempting to save every penny by making sure roads follow hills. However, a road solely following hills just for the purpose of saving money on maintenance ignores the original point of roads - to move units around faster. If you're being attacked in a less defended area, you'll want the rest of your army to be able to reach there in time, not have to run around half a continent!

Slingers aren't that good!

True, the promotion carries on upgrade. True, it can keep ranged units safe from harm. But ultimately, the Incans play best defensively, where the ability to retreat on hit is dimished by all the rough terrain. It's not the end of the world if you never build any Slingers.

Don't avoid settling adjacent to a mountain just to free up a hill!

It's better to found a city adjacent to a mountain than not, even if that involves giving up a good Terrace Farm spot. +50% science from Observatories is too good to pass up.

Growth bonuses aren't food bonuses!

As mentioned before. Food grows your cities, but also acts as a cap on the maximum size of your cities. Growth bonuses will speed up city growth (obviously) but they do not increase the total amount of food a city has. Growth bonuses do not increase a city's maximum size.

Humongous cities aren't always desirable!

This is the toughest point to make. Having huge growth in the early game is very useful to fill up your cities' working areas early, and in the mid-game, fills up specialist slots. The problem is, really huge cities will just spam unemployed citizens. As such, until you have Secularism from the Rationalism tree and/or the Statue of Liberty wonder, it may be best to slow down the growth of these multimillion cities in favour of less-huge cities which can use up your happiness for more productive ends.

Once you have the Statue of Liberty, your unemployed citizens will be worth 2 production, and Secularism adds 2 science, hence making unlimited city growth fairly useful once more. After all, all that production will get Spaceships up quickly.

Don't forget luxuries!

I'm guilty of this. The problem is, the best city spots for Terrace Farms are often full of hills and mountains, and lack luxury resources. Ignoring them will prove detrimental to your happiness, and unhappiness means slow city growth.

No-one can build a bigger city than the Incans in mountainous terrain. But their heavy reliance on such lands will be their undoing.

Playing against the Great Andean Road

Incans defend well on their own ground with better movement in hilly areas. However, come into open terrain or forested flat land and the bonus is gone. Particularly later in the game, with Artillery and fast units as run-in-run-out spotters, you can attack cities safely in open terrain away from all those hills. Alternatively, you can fire over those mountains they like to hide behind so much by that point.

Earlier in the game, use the predictable nature of hills in Incan land to your advantage. Units with rough-terrain promotions will be particularly effective, while you can still utilise the defensive bonus of their hills to make your fights last longer.

The road-maintenance part of the trait encourages extra-long routes, possibly between dispersed cities. Pillaging routes outside their lands is a way to cut off cash for a few turns without going into war. Even better, you could choke off that route by planting a city there, especially if you're a wider-building player.

Playing against Slingers

Slingers are lovely opponents to be up against for their glaring weakness - ranged attacks hitting them. Lower strength than usual coupled with the fact their advantage doesn't work on ranged attacks makes them an easy target for your own Archers and Chariot Archers.

Aside from that, you could use the retreat mechanic to ruin their army's composition. Standard Melee units particularly have a high chance of forcing a retreat. Getting behind the Slinger (or promoted Slinger) lets you push the unit towards the rest of your army!

Playing against Terrace Farms

Why are Unique Tile Improvements better to play against than Unique Buildings? Because you can pillage them, that's why. Mountains make it harder to reach your pillaging unit, too (especially if the city's on one size of a range and your unit's on the other.) Doing this could lead Incan cities into starvation with the collossal amount of food lost, which certainly puts a dampener on their plans.

One crafty trick is to take luxuries relatively near mountain ranges, but not the ranges themselves. This steers the Incans into settling sub-optimum cities which may lack happiness from all the missing luxuries. Let their excessive growth be their downfall!

Mountain settling and high growth itself promotes Science building, but this will come at the expense of Wonder building. Particularly if you're a cultural player, consider taking some of what would be their major wonders (e.g. Porcelain Tower, Temple of Artemis)

A point about Carthage

Counter-strategies to the Incans wouldn't be complete without Carthage, their worst nightmare. If you're playing Carthage, you can get a mounted unit over a mountain and pillage in the same turn - on large mountain ranges, they'll probably not be able to react before you can pull back your unit again. As pillaging non-road improvements heals health, you can do this even on thick tile ranges (as you recover some of the health lost from staying on a mountain.)

Besides that, you can easily surround cities which to other Civs would be chokepoints - thus the Incans may be prone to neglecting defence in those areas.

Strategy by Style

Early or Mid-game Aggressors

Force the Inca to play on your terms - lure their units into open terrain. Plant Archers on hills - it not only allows them to shoot in other hills and forests, but it also provides defensive bonuses. Take advantage of rough terrain-focused promotions.

Late-game Aggressors

Artillery units are your friends. Additionally, hills and mountains do little good against stacks of planes. When the city's weakened, move in for the kill with an Armoured unit, overcoming movement limitations of hills.

Cultural Players

As mentioned before, steal their best wonders before they find the time to build them.

Diplomatic Players

As a scientific nation, City-States may be neglected somewhat as they provide little directly helpful (the cost of bribing Maritime City-States isn't worth it when you've got Terrace Farms.) They won't compete directly with you, but they may threaten you with fast technological development. Cover the development gap with a unique unit from a militaristic City-State if you can manage it to avoid them invading you with their tech advantage.

Scientific Players

The Inca can't have all the mountains, you need them for Observatories yourself! You could always try intimidating them by placing a few defending units in those areas, particularly on what would be optimum Settler spots for them.

There are four other guides based on Gods and Kings mechanics available. After Brave New World comes out, these guides will be kept in their current form for the sake of players without, but updated versions will be made to account for changes.

Carthage
The Huns
The Mayans
Spain