How to stop the deity AI from expanding towards you in Civ5?

Anybody who has tried defeating the deity AI in a domination game is aware of the challenge they are undertaking. Personally, I have found it to be extremely frustrating, and there are times when I screamed at my monitor because of how insane the AI is.

For example:

a) On turn 11, I meet the Iroquois who greeted me with: "Peace be with you..." 5 turns later an Iroquois army emerges out of the bushes and surrounds my capital and KILLS me in 3 turns!

b) I discover that Suleiman has founded a city right next to my capital! I quickly purchase a tile that contains one of my starting luxury resources. He is obviously upset and even after apologizing he declares war against me! And overruns me with Janissaries!

c) In another game, I befriended Pachacuti who emerged as the strongest player in the game (luckily for me). After many turns he says: "I have had enough of you..." and DENOUNCES me! He then sends a great artist to one of my cities and STEALS my coal and iron!

d) I hate Montezuma. In one game that I played, he founded a trail of 12 (TWELVE!!!) cities, 2 tiles apart from one another, all the way to my capital and then overran me! His empire was akin to a phallus that was being driven into my capital.

e) In a game that I was playing, Washington's empire was so vast and his army so huge that his units began spawning in unclaimed tiles in my territory because his army already occupied every tile in his own lands (I knew this because I sent a caravel there and was disgusted by what I saw)! After two mobile SAMs and a giant deathrobot had spawned in those tiles he ATTACKED ME!

f) BUT THE WORST, the very worst thing about the deity AI is their greediness. Given the chance, they will STEAL the land closest to you. It is not uncommon, in a late game, to find that several of your cities are completely enveloped by their borders. And if you dare buy the land near them they will KILL you!

So my question is: how do you stop the AI from aggressively expanding towards you so that you can peacefully grow your cities? And also, why does the AI insist on building their cities two tiles apart from one another? Granted, it makes it more difficult to capture these cities but it also means that these cities need to share many tiles with adjacent cities, stunting their growth and greatly reducing their productive output. I have tried rushing the AI but when I arrive at one of their weakest cities they immediately buy walls, a castle and a catapult to defend it making it impossible to capture with my modest-sized army.

Update: I can't very well mark my own answer as correct since that would be conceited! So congratulations agent86 and to everybody who participated in this fruitful discussion.

Solution 1:

At the higher difficulties, I've found that the only way to win is to play defensively. Siege units, at least one in each city, probably flanked with another siege unit (or two on a border with an aggressive enemy) and some front line infantry is really the only protection.

My second city is almost always founded in an area with a lot of production bonuses (hills, iron, stone/marble, horses/cows/sheep, etc) and focuses completely on producing military for the entire game. If you grow large enough, founding an additional city of this type can be useful, but if you've got around half a dozen cities or less, one is generally sufficient. Have this city crank out units and only build military buildings there (ideally by rushing them, if you've got the cash). Most of the rest of the empire is money- and happiness- focused, although they might churn out disposable units if war is looking inevitable or going poorly.

When it comes to science, pick techs that get you closer to:

• Money production buildings, like the Bank
• Better siege units (trebuchet, cannon, and especially artillery)
• Better front line infantry (musketmen, infantry, mech. inf., etc)

The AI will become increasingly aggressive towards you if they feel your military power is less than theirs. However, they're terrible military strategists. They will send their entire army right to your cities, with no regards to how that leaves their defenses or how positioning effects their chances at survival. At the higher levels of difficulty, this can mean an almost constant trickle of units.

However, they tend to fail to prepare for the bonuses you gain for fighting on your own turf - take these whenever possible, and then turtle heavily when they declare war. After a while, you'll have an army of extremely powerful units (ie, 2-shot per turn siege units with extra combat range, etc) and great generals, which you can use to push the tide back. Plan on cranking out front line infantry units, as they're somewhat disposable. Put a large priority on preserving your high-level siege units, though.

Likewise, if you see a weak neighbor, go after their stuff. The AI gets big bonuses to production, so their cities are going to be better equipped than ones you could found yourself. Declare war, turtle for a few turns while they bumble about ineffectually at your borders, and then steamroll.

Just remember not to completely abandon your own defenses...

Solution 2:

We are all in agreement that the deity level A.I. are ruthless rivals. Placing might before right they are without honor but they are not without equal. Here is what I have learned from your comments and from my own triumphs and defeats against these monsters. I also give attention to the A.I.s aggressive expansionism in answer to my original question.

Maintain an army as large as your economy permits

The probability of war with an A.I. player is determined by your army size relative to theirs. Even if you are able to gain favour with your A.I. neighbours if your army size is lacking they will see you as easy sport and KILL you! As Vegetius teaches, Let he who desires peace, prepare for war.

Expand your borders at low cost

Watch for rival settlers and increase your border growth as much as possible. Upon founding a new settlement always build a monument at this settlement and build as many culture generating buildings as possible. If you see a rival settler approaching buy any unclaimed valuable tiles before that settler founds a settlement. Failing to do this, and purchasing large lots of land after the rival settler has founded a city will anger the A.I. and will increase the chance of war. Do not purchase land unless it is strictly necessary. Purchasing tiles is expensive. The cost of future tile purchases is calculated cumulatively so save your gold, and purchase only strategic and luxury resources and tiles that prevent your rivals from expanding near you.

Naval civilizations are best

Since the Battle of Hastings in 1066 England was never conquered or settled again. Why? Because England possessed a navy and as an island was a very difficult conquest. The French, Germans and Spanish knew all too well that The Wooden Walls of Old England were a formidable defense. Now, in Civilization V we are not always endowed with an island on a Pangaea or Terra map type (the only maps really worth playing), however, when playing England there is an excellent chance that you will spawn next to the ocean. Use this advantage well and settle peninsulas, islands and isthmuses; areas that make surrounding a city difficult. I tend to found cities on one tile-sized islands and then purchase the territory on the mainland. Any enemy embarked unit that is foolish enough to attack my island fortress will drown at sea in the attempt or be killed my navy and/or city garrison.

Containment and Conquest

Sometimes a rival civilization's growth cannot be checked. In that case, war is your only recourse lest the civilization be allowed to continue expanding and kill you later in the game. If you can rally a friendly civilization to your cause and gank this idiot the odds of success will be that much greater. Before declaring war, I reccommend the following:

i) Mobilize your army and prepare to lay siege to any key cities but be aware that if you are scouted beforehand the rival civilization will ask you whether you are preparing for war against them. If you assure them, "Our units are merely passing through" and subsequently declare war a few turns later you will be feared and hated, and your treachery could provoke an unwanted war.

ii) Just before declaring war, change the production focus of every city you own to gold. Ensure that most of your trade agreements have expired with the other nations and offer and loan as much money from your rival as possible. Thus, if you have 12 iron and 4 luxury resources and an income of 50 gold per turn, offer these all to your rival in exchange for as large a sum of gold as possible. Then, once you have traded these away, declare war. All your trade agreements will be immediately cancelled and you will regain these resources much to the dismay of your idiot foe.

iii) Gauge where the enemy is, and fortify your standing armies position's. Do not attack just yet. If the enemy does not attack your sieging armies send a cannon fodder unit into their territory to draw their armies towards you. The AI will attempt to destroy your sieging armies. Having entrenched yourself near the enemy, meatgrind the enemy to death. Use horsemen and ships to pillage your enemies lands, sea resources. Give your enemy no quarter: salt the fields, burn his villages, and destroy his capability to wage war. Your theft of his gold may have already substantially weakened him.

iv) Once the enemy has exhausted his armies against you begin your siege in earnest. Annex one of their cities and use your coffers to purchase units with your idiot enemy's gold. If possible, try to conquer your enemy's capital and as many of his cities as you can. DO NOT conquer your enemy totally or you will be hated and feared as a conqueror by other nations. Leave your enemy at least one backwater city.

v) Once you have negotiated a peace treaty, your empire will have suffered some unhappiness. Mitigate this by selling your conquered cities to your neighbors. I have sold cities and made in excess of 6000 gold from the avaricious A.I. which I used for trade agreements and for future wars. Keep those cities which you feel are of strategic and commercial importance. Build settlers at these cities and raze them upon settler training completion and refound the city. In this way, you reduce unhappiness and don't have to waste your gold on courthouse's to keep the the ungrateful, philistine conquered citizens happy. Remember that those citizens made units for your enemy and that those units killed your gallant soldiers. Be a racist and preserve your nation's racial and culture integrity by exterminating your conquered people's cities.

vi) Inform your conquered foe not to settle near you. Tell him to f**k off with his settlers somewhere else. If he is sufficiently weakened he will acquiesce and you can turn your attention to other matters.

Be North Korea: forbid open borders

Do not under any circumstances give open borders to your rivals. Your rivals will abuse this right and found cities in unclaimed lands that were previously inaccessible to them. There is one exception to this rule, and that is when you are fighting a protracted co-operative war and need coalition friendlies to defend you and allow them to carry their war through your lands to the enemy.

Humanity Prevails!

Facing a deity level A.I. can be demoralizing, frightening and can make you question your worth as a human. Take heart. We are the fathers of artificial intelligence engines and they owe their existence to us. Do not anthropomorphize the A.I. Beyond the wails of Montezuma and his peanut gallery is some crappy Lua programming. The AI cannot learn or feel and it is this that distinguishes us and ensures victory over the deity AI.

My apologies in advance for the length of this post. Perhaps this knowledge will avail itself to other noble humans in future. Humanity prevails!