Dear Lord, Civilization. This series has suffered from a great deal of this since its inception. It's gotten a lot better, but the AI leaders often make astoundingly poor decisions. While part of it is intentional as part of the AI roleplaying according to a certain character profile, most of it is not.
- For instance, nuclear strikes against a fortified opponent or picking fights with someone with vastly superior technology.
- Refusing free money if they hate you enough. ("We would rather eat dung than accept your offer!")
- The AI also doesn't know how to properly build up cities, instead relying on built-into-the-AI bonuses. While you wasted your time building up your economy, the AI is just blessed with an economy and can focus on military build-up. (You're probably going to have a technological edge, but see further down the page for answers to that issue...)
- The AI was usually a pretty bad judge of their inherent value. The ability to exchange cities via diplomacy (added in Civ 3) could be exploited to great effect, either to bleed an opponent dry simply by taking the same city over and over again, selling it back each time for massive profit, or merely as a way to dump a crappy city that is doing you more harm than good. In either case, the computer is more than way too happy to take it off your hands. A patch mostly removed this, so that A.I.s wouldn't include cities in trades any more, although they will include cities in peace treaties, and are still fine with you just giving them a city.
- The AI also often give away every single city except one (their capital, or a random city) if they are losing in a war, as part of the peace agreement. If you are in a war against 3 opponents and they all surrender at the same time, be prepared for unhappiness.
- In the Civ 3 Napoleonic Wars scenario, it is possible to win on the very first turn, even on the hardest difficulty. As Britain or France, you can convince every independent AI to give you all of their cities save one each, in exchange for defensive pacts. Upon hitting the spacebar, you then win a domination victory.
- Another bit of stupidity in III: The AI only cares who declared war, not what caused war. So if you provoked your neighbor civ into declaring war by repeatedly trespassing on their land and spying on them, the other civ will be seen as the aggressor and you will suffer no diplomatic penalty. This allows for some delicious Wounded Gazelle Gambits: get a Mutual Defense Pact with the neighbor (let's say Greece) of the civ you want to fight (let's say it's Rome); trespass on Rome's land and make the Romans extremely insulting offers until they get Furious at you; run one espionage mission, which leads Rome to declare war on you; and then merrily invade as your ally Greece declares war on Rome too (because technically, Rome attacked you, not the other way around) and now the Romans are fighting a two-front war. Ta-ta, Caesar!
- Adopting "Fascism" in III will knock a few population points off every medium or large city, as a rather chilling abstraction of your government killing "undesirables". The computer is programmed to value Fascism very highly as a war government and if possible will almost always adopt it at the first sign of conflict. This leads to the AI literally genociding themselves into irrelevancy as they constantly swap in and out of Fascism during the inevitably politically turbulent Industrial Age.
- Beyond the Sword expansion pack of IV adds diplomatic features that the AI players tend to use extremely badly. For example, they will gladly cast their Apostolic Palace votes in favor of ending wars — even if they declared those wars themselves and had vastly superior armies.
- In Civ V, the AI seems all too happy to repeatedly insult someone who A) is decades, if not centuries, more advanced than they are, and B) has already conquered several other civilizations. Then, they act surprised when they're next.
- Also from V, there is already one report of an AI (specifically, Oda Nobunaga) sending their entire army against a city-state only for it to be routed by the city. This is made much more annoying for the guy who witnessed it because said AI was their teammate.
- Nothing tops Civilization V's Worker units. When automated, they do whatever makes sense to them — for instance, if (say) Townsville is at zero growth, meaning it has exactly as much food as it needs to sustain its population, and it accomplished that by putting farms on some hillsides... the Workers will go on ahead and turn those hills into mines, resulting in instant death-by-starvation in the city. And if you tell them not to, well, you're bound to Automate them again, at which point they'll return to that hill and mine it, by golly! — because you may be the ruler of an empire, but only Workers know what a city actually needs! Thankfully, The "Workers leave pre-existing improvements" option from Civilization IV has been patched back in.note
- Workers will not only remove usual improvements, but also occasionally remove incredibly expensive "great tile improvements" that take dozens of turns to have a go at building — only to replace them with a farm or a mine.
- Citizens (for those who are a fan of even more minute micromanagement... and raging at the inefficiencies) seem to value any tile yield equally, and maximize based on quantity not quality of yields. This means that while Gold is typically considered the lowest-value early game resource, Citizens would prefer to work a luxury resource tile with three gold, one production, and one food over a typical improvement's two production, two food tile (which would clearly help growth more).
This behavior bleeds through to Worker AI, most clearly seen by their love of Trading Posts. During Golden Ages, which give an extra Gold from all yields, Trading Posts jump to a three gold improvement in the late game while farms and mine typically give two food or production respectively. This means that automated workers will gleefully build Trading Posts on every freaking tile. Without some of the AI's Special bonuses on the higher difficulties, expect them to be weak, bankrupt (as there aren't even enough citizens to work their Trading Posts that are built from the second new cities are established) and technologically backwards past the 250 turn mark. - The town border expansion by culture is also suboptimal. It will sometimes ignore valuable luxury resources in favor of tiles with the same cost and only initially better output in resources, such as water tiles. This is somewhat deliberate as it means the settling patterns or the civ's people is slightly at odds with the prosperity of the civ as a whole, and "gold" can be used to claim tiles.
- Workers are smart enough to run to your cities when land-based barbarians show up, but due to embarkation allowing them to cross oceans to work on the other cities in your empire, they'll go right ahead and embark into barbarian-infested waters. Also, AI civs you are at war with will occasionally charge at you with workers; this effect has been lessened with patches, but there are still opportunities to grab unprotected workers here and there.
- Many reviews of V have commented that the AI is quite poor at strategically placing its military units. Apparently the game's own AI hates the new stacking rules.
- Another issue with the stacking rules that was seemingly overlooked by the developers is that a player can use their units to simply block AI units, and that AI will not get angry. For example, if an AI is at war with someone whom you don't want them to defeat, simply place a few units in the way, and it will heavily reduce their ability to swarm that defender. In another sneaky trick, you can block AI Settlers (especially near your borders if you don't have Open Borders), and the AI will not build another Settler to expand because it thinks it's still got a perfectly viable one right there. Do this early enough, and you will cripple that AI Civ because it won't be able to make any additional cities. It's interesting, because the developers realized that having a large number of units remotely close to another Civ's border might be indicative of war, but the AI never realizes what you're doing to demand that you stop blocking their units.
- Related to that, the AI seems to suffer from the calculation of relative military strengths not taking concentration of force into account. One civilization could have a greater total amount of military strength on its side by way of having lots of low-tech units, while another side has less total military strength, but what strength it does have is centralized in a small number of higher tech units. This leads the AI leading the more primitive civilization into war with the more advanced one where their larger army will get picked apart piece by piece by the much smaller, better equipped, force. Your Military Advisor calculates by the same means, urging you to make peace while you are wiping the floor with such an enemy. This problem also make Domination victories an exercise in frustration when you have AI teammates because it means that they regularly make peace with a side you're about to finish off (or at least get good surrender terms with) without even consulting you and thus forcing you to honor a peace treaty that you got nothing out of.
- The AI also fails at realizing that indirect combat units cannot capture towns, bringing little or no direct combat units to lay siege to a town. Pick off the direct combat units and you can decimate the rest with the town defense and a ranged unit stationed in it. Alternatively, the enemy will primarily bring only direct melee units and bash themselves to pieces against the city walls rather than fortify and wait for the ranged and artillery units to soften the city up.
- The AI doesn't seem to take into consideration any terrain issues when declaring war. So, you'll see plenty of AI Civs declare war on you and then try to march their troops through forests, hills, jungles, and marshes to get to your cities, allowing you to easily pick them off one by one as their reinforcements lag behind them. They also don't seem to consider how fighting someone with the Great Wall has the same effect, but worse since the defending troops aren't likewise hindered.
- Finally, both the AI and military fail to take into account productive capacity—i.e., the ability to build units—and most especially, build a large number of units quickly. This capacity can be even more important than the number of units at the outbreak of war (real life history: World War II, USA and USSR). Civilization VI shows this issue particularly glaringly with its Australia civ, to the point where it borders on A.I. Breaker. Australia gets doubled production capacity for ten turns upon receiving a declaration of war, but the AI doesn't seem to factor this in at all, frequently declaring on Australia's inferior military and running into a brick wall when a defensive force is assembled on demand by the time their armies get close.
- Another thing about the AI in V is how stubborn it tends to be. Imagine a Civ declares war on you, then you curbstomp their armies and take several of their cities and your armies are waiting just outside of another one of their cities and can take it easily. You'd imagine that when you give them demands for peace, they'd accept your conditions should they be reasonable. But no, anything other than an unconditional peace agreement (or one that doesn't favor you) is completely unacceptable. They won't even give you 1 gold if it means you will stop taking their cities. On the other hand, imagine the same situation, but they are demanding an insane amount of luxuries, resources, and gold from you to end the war. Or they demand such things even if they have yet to go into battle with one of your units.
- China's Chu-Ko-Nu's can fire twice in the same turn, making them practically game-breaking in the hands of a human player. The AI often manages to completely forget this, turning one of the best civs in the game into a complete joke.
- No matter what civ they have, they will always go wide (making lots of small cities), even if they have a civ meant to go tall (making a few very big cities). Then with "Brave New World", we have Venice, who literally cannot make more than one city as part of his gimmick. As you can imagine, this causes the AI to completely crap itself and never be a remotely competitive force in the game. In particular, expect them to never use their Merchant of Venice's "puppet a city-state" ability; there's video of the Venetian AI conquering a city-state through a grueling military campaign rather than walking the merchant over and hitting one button.
- Units set to "Explore" have some of the dumbest AI in the game, running an algorithm that only accounts for terrain hidden versus terrain revealed, not silly little things like whether they'll start a war with a City-State by trespassing, or whether they're slowly circling a Barbarian Archer and getting themselves shot to pieces. Not only that, but they will also wander until they get stuck at the north or south pole and will continue to move one space towards it and one space back because they are unable to explore the ice fields. They do this despite the fact that there's other places they can go to explore. This problem is only solved when you get submarines which can explore under the ice and won't get stuck. However, if you weren't careful, this won't help you with exploring land that you missed earlier and scouts are so out-of-date by this point that they can be one shot. In VI this is "fixed" by just switching the unit to manual control and getting the player to deal with the situation.
- One of the best conquerors in recorded history, Alexander the Great's entire kit revolves around attempting to overpower other civs through war or diplomacy. However, his AI is just brain-dead stupid. He prefers faster units, such as horsemen, knights, etc., which are weaker when attempting to attack cities. As well, he is better friends with you when you're a warmonger, and he will likely keep an army at the ready, just waiting for a reason to go to war.
- Pay a Civ to declare war on someone (ideally a weak, but not "too" weak civ) then join in - it'll give you a diplomatic bonus as it'll make the world think you're helping out the poor underling fight off the Big Bad when, in fact, you masterminded the whole thing.
- Nebuchadnezzar II. Babylon is considered one of the most powerful civs, because its ability, Ingenuity, gives them a Great Scientist much earlier on than anyone else can even think about one. Great Scientists have two abilities, both of which consume them. They can build an Academy, a tile improvement that provides a continuous and considerable science boost; though it's a drop in the bucket later on, it often more than doubles it at that stage in the game, allowing you to pick up every other Ancient Era tech in just a handful of turns. Or, they can use a Discover ability, which provides a one-time science boost based on your current output, usually enough to put you most of the way to the current tech you're researching. In the hands of a human, who will use the former ability a lot in the early game and the latter in the late game, Babylon can easily snowball until they have tanks when everyone else has knights. Yet when you conquer Nebuchadnezzar with surprising ease, you likely won't find a single Academy in his whole territory, implying he thought learning Archery right now was more useful than halving his time to it and every other early-game tech.
- Even with the greatly improved naval combat in "Brave New World", the AI does not know how to properly conduct a marine invasion. Play an archipelago map and watch the AI send dozens of embarked land units at you without escorts, which naturally leads to them being utterly massacred if you made even a token investment in actual combat ships, and leaves the attacking civ nearly defenseless for when you counter-invade.
- The AI does not seem to know ranged units can move and shoot in the same turn, thus wasting much of the units' potential.
- Related, the AI does not realize that endlessly fortifying against a ranged unit shooting at them will result in the unit eventually dying unless they gain reinforcements. Get prepared in the early game to see a LOT of AI spearmen holding defensive positions against Barbarian Archers and the like rather than simply marching over and slaughtering the guys poking them full of holes.
- In the World Congress, two of the potential options to propose are Arts Funding and Science Funding. Arts Funding boosts the production of Great Artists, Writers, and Musicians and drops the production of Great Merchants, Engineers, and Scientists, while Science Funding does the reverse. Generally, the former three units, though not useless in other hands, are most effective while aiming for a Cultural Victory (since they increase tourism), while the latter three are more useful for everyone else. Despite this, the AI seems to really like proposing and voting for Arts Funding, even when its civ has no interest in tourism whatsoever.
- Civilization Revolution:
- Not so much costly errors as wasting of real time, but sometimes units on roads will, within a single turn, repeatedly go back and forth on the road until who knows when.
- Whenever you tell a unit to go somewhere more than one region away, it will plot a way to get there, taking into account the terrain it can cross vs. the terrain it has to encounter... but not allied borders until you get there. Allied borders may not be crossed without starting a war, and if a unit you just told to go somewhere without guiding it around borders may try for a little bit to found a way around, but will then forget everything it's learned and charge at the border again, only to be deflected. If you don't Cancel Move, it will waste many turns doing that.
- Purchase the Democracy perk and your production and culture increase greatly, but at the cost of your Congress vetoing you whenever you try to declare war or refuse peace offers from rival civs. The other civs understand this limitation, and will liberally abuse it by attacking and capturing one of your cities, quickly offering you peace so you can't do anything about it, and repeating the process from there. And Congress never lets you refuse the peace offer or launch a counter-attack to reclaim your city, no matter how obvious it is that you're being played.
- This works right back at them so long as they stay in Democracy. Most A.I.s refuse to let a war declaration slide and will not give you peace until at least one turn passes (even though they should be forced to, they cheat), giving them a turn to switch out of Democracy before deciding. However, combine this with the Great Wall wonder (enemies cannot declare or remain at war with you while it is in effect) and you can hogtie the AI while it cannot even lift a finger against you, and forgives your every action.
- The A.I.s are normally pretty good at guarding their settlers. Caravans, spies, and Great People? Not so much. They regularly lose caravans to stationary barbarian huts, will leave any spies they capture sitting in the exact spot they took them from you, and only rarely place their own spies to protect their own settled GP. Even on Deity.
- The AI creates exceptions to settler guarding rules. IF they don't see any enemy units nearby, they'll let their Settler (2 moves) outrun its escort unit (normally a defensive unit like an Archer, 1 move). While this is more foolhardy or risky rather than stupid, the AI normally keeps such a tight grip on its Settlers that they'll sometimes march an entire army out with their first Settler, leaving only a single defending Archer or Warrior to defend the city and you can guess what happens next. Especially if you are sitting nearby waiting for this happen with a horseman army or two...
- More rarely: When an AI unlocks a new defensive unit tier (like Pikemen after Archers), it will attempt to upgrade its defenses ASAP in any way possible. In Civ Rev, units cannot be directly upgraded with gold, however you can sell units and use the gold to rush new ones. The problem is, you can only rush one unit per city per turn; armies require three units to form. So you'll sometimes see these fantastic blunders where the AI will sell its Archer army (or armies) to pay for new pikemen, but leave itself vulnerable for a few turns while it only has single units defending instead of an army, which is much stronger.
- Once an AI gets Flight, you can expect them to gloriously kamikaze their fighters into the nearest city defender as soon as they can when at war with you. Nevermind that Fighters are meant to specifically counter Bomber units, and are better at picking off vulnerable units like single ships or offensive units that have much lower defense than defensive units in cities. Or that even if they beat the defending units, that air units cannot capture cities.
- Rather amusing one: What happens when an AI is exploring with a boat and gets blocked from where they are trying to go by borders or units in the way? Why, they sell it of course! Why bother going another direction or recalling the boat for another function elsewhere, after putting those resources and turns into it? It would be much better to sell it immediately for considerable loss in the exchange rate of production/gold and those turns burned away irreversibly, right?
- Civilization VI:
- Civ VI is notorious for Breaking the Fourth Wall by having AI opponents declare war on you for no reason other than because you are too close to winning the game, even if they were complimenting or even tributing you a few turns before. Even Gilgamesh or Tomyris, who are supposed to like long-term alliances and avoid backstabbing you, will happily go to war with you if you're winning. Any kind of diplomacy has to allow, not just for the other leaders' own intelligence, but for the game's overall agenda; and any victory other than military becomes exceptionally difficult, because no matter how nice you have been, every country will try to wipe you out if it will stop you reaching a victory condition.
- Before a number of patches and the Grievances system, it was amazingly easy to get into a cascading downward spiral of diplomatic penalties because of the AI's shenanigans.
- Firstly, doing anything that ran counter to an AI player's Agenda would be functionally a Berserk Button.
- The AI would forward-settle one of your cities, then complain that your military units were too close to their borders. Said military units would usually end up being the garrison of the city the AI just settled right next to.
- If a less technologically advanced AI neighbor declared war on a player, and the player started winning that war, the other AI would get angry at the player for stomping all over lesser Civs.
- The AI just doesn't seem to "get" the Loyalty system introduced in Rise and Fall. It will happily settle cities on the other side of the continent from their closest settlement... and since settling far away from your cities and close to enemy territory will cause a massive drop in Loyalty, the AI will lose those cities to rebellion a few turns later, perhaps in the player's favor. The saddest part is that there's not much the player can do not to exploit this: they can refuse to accept rebellious cities into their empire, but that doesn't make it much less of a loss for the AI. (This is arguably a step up from the vanilla system, where the AI would settle next to you, arbitrarily declaring your corner of the world to be "their territory," and then have casus belli when you continue to expand around their intrusion.)
- Gathering Storm changed the strategic resource system from a binary "as long as you have one copy you're set" to an accumulative "one copy gives you this much per turn, you have to spend X amount for a unit", similar to gold or faith. However, the AI that shipped on release had some major flaws on how they value these resources:
- It's possible to convince the AI to trade you some gold for a resource, then trade you said exact same resource for less gold than what they gave you. You can continue to sell their own stuff back to them until they run out of money. Let's Player The Spiffing Brit weaponizes this technique here
. - The AI does appreciate that various Strategic Resources becomes less important with time, but it doesn't get the idea that eventually become obsolete. If the AI wants to buy ten barrels of oil off you in the 20th Century, you can probably swap that for thirty iron and thirty horses despite ten oil being far more useful to your civilisation at this stage (not to mention that you'll get those other resources back quicker).
- Thankfully, later patches fixed both of these. The only downside is that now the AI will ask for such an exorbitant amount of gold for you can basically forget trading to get any.
- It's possible to convince the AI to trade you some gold for a resource, then trade you said exact same resource for less gold than what they gave you. You can continue to sell their own stuff back to them until they run out of money. Let's Player The Spiffing Brit weaponizes this technique here
- Barbarian and enemy units sometimes kill themselves on stronger player units. This is especially true after destroying a barbarian encampment, in which all barbarian units go berserk and attack the closest unit they find.
- Sometimes the AI sends settlers unescorted and get them captured to the barbarians. Their solution? More settler spam! ...And they're in the hands of barbarians again. They're left with only one city, therefore backwards in science and weak in military as a result.
- Kupe of the Maori, who were added in the Gathering Storm expansion, are unique in that they start on the ocean and travel before finding a place to establish their first city. Unfortunately, the AI isn't very good at playing as Kupe with this mechanic, and is thus prone to settling on the first land he finds, which can often be an inhospitable patch of ice or a one-tile-wide island in the middle of the ocean.
- Civilization: Beyond Earth carried over all the issues of Civilization V, but sometimes tried to fix them by making them worse in the opposite direction. Particularly annoying when a faction would trade a tiny, useless resource only if you give them half of all your precious assets, and nothing else. Or when they avoid confrontation if you are militarily superior, but when in war they utterly refuse to make peace even if you pay gifts.
- The expansion Rising Tide overhauled the diplomacy system with more advanced interactions and introduced a new almost game-breaking bug: everybody is forced to follow their allies in their war, against anybody, no matter the situation. Normally, when one of your allies goes to war, you should be immediately asked if you want to join them or dishonor the alliance (best would be that only afterwards your ally might or might not contact you asking to honor the alliance, depending on what's needed). Instead, you're forced to follow your ally to war, without a word in the matter, which might not seem like a problem at first. It could be an understandable design choice... if your ally would at least make careful decisions, as opposed to sudden nonsensical moves against much more powerful factions, even ruining your complex web of treaties and commercial routes. But things become completely absurd if two of your allies wage war on each other: you are forced to honor BOTH alliances, so you end up at war against BOTH of them. If they have other allies, the resulting cascading alliances might easily turn the game into an ALL v.s ALL perpetual state of war. You are not even asked which side to support, ending just one alliance, which would have been the most logical consequence. This forces you to renounce all alliances (and thus a major part of the new overhauled diplomatic system) to avoid this situation. But then other leaders criticize you for breaking treaties, and your former ally now inexplicably hates you and declares war on you... this oversight has never been fixed.
- The affinity system should in theory feed alliances with factions following the same affinity and prevent the contrary, adding ideological and political flavor to the game. Yet most of the times you still get alliances with factions that have completely different affinities, which only give a minor malus in relations among tons of other influencing factors. This is particularly evident when you ally someone in the early game and the two of you later develop opposite affinities, as the AI will be reluctant to even consider that your nearby civilization is doing everything your citizens despise. An allied faction pursuing only the xeno-friendly harmony affinity will only send a few text complaints if your purity or supremacy game is terraforming everything, killing wildlife and polishing miasma, if you (easy to do) still manage to get good relations overall.
- Sid Meier's Alpha Centauri also has its instances:
- Even on the higher levels of difficulty, the AI will often agree to obviously unfair city exchanges- like trading their densely-populated city in an area rich with resources, housing some Secret Projects, for some sea colony newly founded, lost deep in the ocean with next to no resources; They are also prone to declaring war on you if you have adopted a civic they hate (like green economy for Morgan), even if your faction is clearly overpowering theirs.
- The SMAC AI also tends to be a bit warmonger-ey, with some civs inevitably sliding towards war with the player (i.e. you) over time. Of course, if you don't have much in the way of a military by then, their overconfidence is anything but...
- The AI also doesn't check whether you have units in your allies' cities and so will launch absolutely stupid surprise attacks against you, by attacking a city that you don't own but do have units in.
- The way priorities are assigned for AI personalities leads to some enormously stupid behavior. For example, Miriam Godwinson is highly aggressive and expansionistic, a combination that often leads to her establishing an excessive number of cities and then completely focusing production to build swarms of weak low-tech units instead of infrastructure. Miriam will also build sea colonies in oceanic trenches, where it's completely impossible to improve the surrounding tiles or get any kind of resource yield.
