YMMV / Hearts of Iron

• Aluminum Christmas Trees: Upon release of the related DLC, the concept of a focus tree giving Estonia oil as a resource was scoffed off as absurd and gamey. In real life, Estonia has huge deposits of oil shale, which it started to use industrially during the interwar period - just not for fuel production.
• Awesome Art: The pre-order trailer. Unlike other trailers which use stock images and footage, this one has awesome Soviet propaganda-styled artwork.
• Awesome Music: Has its own page.
• Broken Base:
  • Changes in logistic system between games are by far the most contested part each time new game shows up or is patched up.
    • II used a simplistic and abstract system that kept track of a "Transport Capacity", a counter equal to twice the IC size plus tech modifiers and difference between stored and used supplies and oil.
    • III attempted to make logistics more realistic. It introduced fuel and required crude oil to be refined to make it, the transport capacity of infrastructure, detours, use of supplies and fuel for the transport of supplies and fuel themselves and bottlenecks. It was an extremely divisive subject. People either praised and wanted more of the details put into it or consider it too boring.
    • IV came out with another new system that doesn't require micromanagement of sending equipment to units as that is done automatically, but has an abstracted infrastructure & unit supply system and after the Man the Guns expansion, fuel for vehicles, planes, and naval units. Changed also was the unit production system. Instead of ordering whole complete units, the player now has industrial production to manage, with abstract "factories" building different types of hardware. Those are then combined to outfit a unit while it is formed and put through basic training.
    • No Step Back came with a massive overhaul of the supply system that now allows countries to build railroads and supply hubs, trains, revamps what motorized does by changing it to a generic truck, and placing a heavy emphasis on "Supply Status," AKA how well-supplied your troops on the frontline are. Again, this has supporters and detractors, with those in favor saying that it adds more to the fun of micromanagement by allowing the player to cut off their enemy's valuable supply lines and makes fighting in mountains and deserts substantially more tolerable, while those who dislike it now complain that everything in the game is about supply, to the point that designing good units, upgrading doctrines, planning a strategy, etc. can be rendered worthless if the enemy seizes a key supply hub or builds enough railways.
  • Numerous elements striving for realism were added in III, like the advanced logistic system, radio range, thousands of land provinces to fight on, extensive command structure, and complete rework on how units are made, followed by the introduction of combined arms mechanics. Some found it great, adding tactical and strategical options, others found it boring and tedious due to the amount of non-combat elements necessary to micromanage. IV came out, streamlined most of those systems, and focused the effect of those on the combat units directly.
    • In addition to the very controversial way Paradox charges for their DLC, the Man the Guns DLC for IV also had an issue with older players who recognized features being re-introduced from earlier games such as the ability to customize naval units, behind the DLC paywall.
  • The BlackICE mod for III makes the game very difficult as it extensively uses all the mechanics introduced in that game and punishes players for overlooking them. People either start twitching nervously a sole mention of the mod and calling it out for being ridiculously difficult with even a higher skill requirement or can't stop talking about all the gameplay mechanics and improvements interacting with each other like a well-oiled mechanism.
  • The exclusion of Manchukuo from Hearts of Iron IV has divided many fans. One side claims that the Japanese in previous Hearts of Iron games have a poorer chance against China, thus eliminating Manchukuo would be the best step in giving the Japanese more edge. The other side are either fans of playing the puppet state in the previous games or want to preserve as much historical accuracy as possible. Paradox Games added Manchukuo in a patch eventually.
  • The planning & battle line mechanic in IV. Early in the lifetime of the game the old experienced users hated the system with a passion, preferring to micromanage every division they created. New players didn't come in with any baggage and were more than happy to use the simple method of adding 24 (or infinite, for Field Marshals) divisions under a General and giving them a piece of the frontline to hold, with very simple "attack this way" lines. And then patch 1.5 happened, which divided playerbase even more. Supporters of planning mechanics got suddenly hit by a cluttered UI and various problems managing the now required multiple unit commands and many considered it more tedious to use than the manual system.
  • While this has been primarily ignored in earlier games, in recent years following the release of IV, there has been growing controversy regarding Paradox's refusal to showcase World War II atrocities, specifically Nazi atrocities such as the Holocaust (especially since Stalin's 1936-1938 Great Purge is portrayed in the game, requires player input, and has actual consequences on gameplay instead of being a mere "informative trivia" event). Proponents of showcasing World War II atrocities argue that not showcasing them feeds into far-right viewpoints surrounding the Second World War that whitewash the crimes of the Axis powers in favor of showcasing their flashy war machines without context, and may potentially play a role in creating a pipeline to radicalization at a time of rising far-right sentiments worldwide. Detractors of the idea argue that it would be poorly executed and done tastelessly if pulled off and that showcasing Nazi atrocities won't actually weaken any potential far-right voices in the fandom, but would instead give them a chance to roleplay their genocidal fantasies. Interestingly, the sole atrocity the series acknowledged was the Nanjing massacre in the first two games, then also making it a footnote in the fourth game as "a city taken".
• Cheese Strategy: Want to justify war on a country, but the Allies keep guaranteeing it? Simple, since guaranteeing costs more and more political power, all you have to do is justify war on random countries in the middle of nowhere and watch as the cost of guaranteeing rises so high that the Allies can't guarantee your intended target anymore.
• Complacent Gaming Syndrome:
  • The series as a whole makes navy and fleets completely negligible. You can always just build bunch of transports to get troops to places, and there are dozens of cheap, near-exploit level ways to entirely disable enemy fleet, without building a single ship yourself. Also, short for Germany and USA (and in Darkest Hour Italy), nobody has any need nor use from submarines, making them almost entirely redundant to research and produce.
    • In IV, most single players don't bother researching surface ships and exclusively build submarines and some form of bomber capable of conducting naval strikes. One because these units are hilariously broken and two, they're simple to use and produce, allowing players to ignore the surprisingly complex naval combat system.
  • It is almost automatic for a player's initial steps in the research tab to select electronic mechanical engineering for the base bonus to research speed, and whatever is available under the industry menu for boosts to production efficiency, factory and dockyard output, and construction speed, all of which pay immediate dividends that continue for the whole game. In any game where full scale war can be held off for at least a couple years, almost every technology or equipment research can be delayed until all industry items are brought up to date.
  • There is the Boring, but Practical unit template in each of those games. There are might be situational variations and highly specific scenarios where you might want to have something else, but they are so good in combat and so efficient to make, there really isn't much point to do anything else.
    • Darkest Hour specific: 1942 infantry with towed artillery and half-in-half of engineers and tank destroyers. Almost all nations can pull this and you really don't need much more. If it's early war, the 1936 infantry with artillery and engineers are all you will ever need, especially when fighting anywhere outside Western Europe. II made it even more boring, since all you ever needed was foot infantry with artillery, while engineers were far less important.
    • III specific: in vanilla and HPP mod, it's two infantry brigades, artillery and engineers. In fact, this one borders on Game-Breaker, given the absurd potency. Later in the war and when facing majors, the 5th slot is usually taken by the cheapo AT artillery.
    • IV specific: 40 width infantry units, in 14:4 infantry:artillery ratio and engineers, recon and AA battalion support. As far as single player goes, this is all you really need to win against even the strongest Major Powers, and you don't need the navy or air force in majority of conflicts, while your infantry will simply gun down the planes by sheer presence. The basic production required for success in almost all land wars are only Infantry Equipment, Support Equipment, Artillery and small handful of AA guns. Even after division composition mechanics have been reworked, the near identical unit with 41 width (13:5 infantry:artillery) is equally efficient.
  • There are many players who only ever play a single nation. Germany is the most popular, as their role is the attacker, which is more fun than a defensive nation like France. As can be expected, there are players who only play in their own home country.
  • In IV, unless you are fighting an early war the default strategy for what to research is pushing Tier 2 Production, Industry, Construction, 2 Electronics + Radio and depending on what country you are and if you're doing a tech rush, going for quick Medium or Heavy Tanks or Fighters. The industry and research techs are vital for establishing your economy, and getting better tanks or fighters is vital for certain nations to have before the Axis start the war against Poland and the Allies in 1939, before the invasion of the Soviet Union usually in 1942, and before Japan takes on the United States.
  • IV has an option to randomize which focus trees countries go down, which can lead to events like a Military Junta overthrowing Hitler, the British turning Fascist, various countries having non-historical civil wars or where aggressor nations like Germany or Japan change from their 'default' strategy. There is a large percentage of players who refuse to do anything but use the historical setting.
  • The higher the difficulty level, the more players are required to restrict their research, production and unit types to the handful of specific elements of the game that make the difference in the ground combat.
    • Playing as the Soviet Union at the highest difficulty requires the player to strongly research & build basic infantry units designed to Hold the Line and the industrial capacity to keep them all supplied until the Germans lose enough units & equipment that their attack bogs down along a Leningrad to Moscow to Stalingrad line. The Soviet Navy is completely irrelevant, and trying to build an air force will just result in them getting shot down in a few weeks and wasting the factories you used to build them. Trying to get cute by giving infantry units too much artillery, anti-tank & anti-air guns or trying to build a huge armored force will just leave you in an impossible equipment deficit once the Germans & Romanians attack, steam-roll their way through Poland and Ukraine, widening the front so much that anyone who didn't create a gigantic horde of defensive infantry units will lose.
  • Space marines^note a division consisting of marines backed by self-propelled heavy artillery and AT guns were so widespread and commonly used (up to the point people didn't build anything else), Paradox had to keep nerfing the related units needed to form them and ultimately, by the Waking the Tiger update, special infantry could be only fielded as a percentage of your total land forces, to keep them "special", rather than a backbone of your fighting force.
  • In IV, after both tank and airplane design mechanics have been changed, the best results are achieved not by increasing various values, but keeping them at such a level, they don't add additional resources to the production (which keeps the production itself cheaper, too). The sheer cost-efficiency of using just steel for tanks and aluminium for planes completely outweighs any gains they could have had from slightly higher stats, bordering on weaponised Boring, but Practical.
  • In a similar vein, making sure that whatever equipment you design yourself is either below 4.5 production cost or at least a multiplication of 1.5. In IV each military factory provides 4.5 production. Any equipment that ends up having production costs not divisible by that value will suffer long-term production inefficiencies, especially when there is some tiny decimal left in the end - it will still require the additional production to finish that equipment, leaving you with a generally slower production rate that also requires more factories, while the carry-over decimal won't materialise into new materiel for a month.
• Discredited Meme: Italy will never get a focus tree, which originally popped up due to how long it took for Italy to get a new focus tree. Obviously discredited by the fact that, well, Italy did receive a rather large one in By Blood Alone that completely revamped how the country works and is actually considered to be quite good and having made the country legitimately fun to play.
• Ensemble Dark Horse: Of the unique Minors, Mexico is a very popular nation due to the quality of its Focus Tree, widely held as one of the best amongst Minor Nations and better than some Majors.
• Fan Nickname: Not wanting to trip the Youtube censorship bots has made it common for video creators on the platform to use a nickname for Adolf Hitler. These include "Mr Schmidtler", "Gamer Germany" and "Funny Moustache Man".
• Funny Moments:
  • The responses to news events regarding New Zealand’s tank research (the infamously terrible Bob Semple and ahistorical Big Bob tanks) for other countries. The Bob Semple Tank is met with mockery of its name (“They call this thing a WHAT?”), while the Big Bob (a super-heavy tank) is said to make the world “tremble…with laughter…”. It seems Paradox is all too aware of New Zealand’s Joke Character status.
  • As Poland, it is possible to get Wojtek as a commander, and even make him king if you go monarchist. For those who don't know, Wojtek is a Syrian brown bear.
• Game-Breaker: Now with their own page.
• Growing the Beard: IV's DLC focus trees at the beginning were mostly just a collection of industrial and army focuses, with maybe a couple of alt-history paths that just turned the country communist or fascist without any actual basis in reality so the player could conquer their neighbors. Modern DLC focus trees typically have a much wider array of focuses to choose from, and the alt-history paths are often heavily researched and based off of real partisan groups and political situations within the country at the time.
• Good Bad Bugs:
  • One patch for Darkest Hour had instances where after the Soviet Union lost a war against the Axis and accepting the bitter peace event, Lenin would take over as Head of State of the Soviet Union, cue jokes about Zombie Lenin coming back to Set Right What Once Went Wrong.
    • Similarly, in IV, if one sent the entire German royal family ahead to participate in the ceremony restoring the British titles, they'll still die and Von Mackensen will take power again. However, if one plays up until his death, Wilhelm III (who is dead at this point) will take over.
  • A in-game overflow error in IV caused a stack of planes to go negative... leading to infinite manpower when you would try and disband the airwing.
  • With the release of the “La Resistance” DLC a new achievement was added that involved Germany conquering France and Poland with 0 casualties in 1939. Players almost immediately found a glitch that allowed the control of AI nations^note In version 1.9.0 it was possible to open observer mode using a loading glitch, thus allowing a player to take control of any nation and straight-up delete the nation's army and industry, as well messing with other things (changing focuses and otherwise screwing the AI). This saw the near-overnight spike of achievements as players could simply delete a A.I.s capability to wage war and repeat the glitch to return to their own nation
  • A bug for IV that was patched: political focuses can be mutually exclusive, which meant that if you did one, the other was locked off (i.e., do Oppose Hitler, you lose the focuses that the fascist branch has). However, if you managed to bypass one of the two focuses, you could access both branches, which would allow you to do some very overpowered stuff^note in particular, there was the aforementioned German focus tree - both political branches could be unlocked by being in a war, which would remilitarize the Rhineland, and let you bypass the focus - which made forming the European Union or Holy Roman Empire very easy, and also the Netherlands - could bypass "Curtail Colonial Autonomy" by annexing the Dutch East Indies; they could be released as a puppet again afterwards - which would allow them to both set up the Dutch East Indies for relocation after the Netherlands capitulated and do the Zuiderzee Works.
  • If you deleted all but one division, exercising it would give you tons of army XP. This was unsurprisingly patched.
  • One branch of Yugoslavia's focus tree has a hidden feature - said tree breaks Yugoslavia down into the various nations that were combined into it, with the last focus allowing the player to re-annex said member states, and if their puppets had any additional cores, Yugoslavia would gain those cores as well - this would also include Bulgaria and Hungary if the player had managed to puppet them^note at its fullest extent, a player could have parts of Czechoslovakia, Romania, Greece and Italy as core territories. However, a bug early on gave Yugoslavia cores on any land occupied by said puppets, meaning that if one, oh say, defeated Germany and gave all of Germany to Slovenia, they'd have cores on all of Germany. This was patched, although if things go certain ways, it can still be very broken^note the ability to core Bulgaria and Hungary means that the player could also core Czechoslovakia and Austria from Hungary if it reformed the Austro-Hungarian Empire, and the rest of Romania, Greece, and Albania from Bulgaria if it unified the Balkans; and of course, Yugoslavia can also gain cores on a few Italian states.
    • A similar, but even more broken, bug involving the Imperial Federation: If one gave the states that make up the British Raj to Australia or New Zealand, the focus would core them - this might not seem broken until you realize how much manpower and factory spots are in the Raj, and that this would also give the player access to all the manpower the Raj has^note India, Bangladesh, and Pakistan have some of the most manpower in the game, but this is balanced out by the Raj only having the first 2 as cores, while Pakistan and Burma are merely occupied; for similar reasons, Malaya isn't cored by the Federation. Again, unsurprisingly fixed in a patch, although similar to Yugoslavia, other cores aside from the ones the Dominions start with by default can be obtained^note if New Zealand and South Africa form their formable nations, the UK cores them as well; if the player goes Monarchist or Fascist, they can have Canada core all of the United States, and lastly, a Fascist UK can form the European Union after forming the Federation.
  • Stalin's Purges in No Step Back have a few rather amusing bugs associated with them^note originally, his purges were reflected with a single, 210 day focus; the new system was more akin to how it was in real life, namely, multiple waves, and you can also do single purges that target a specific general; the latter can also occur as random events.
    • It's entirely possible for a general to accuse themselves of being disloyal. As such, you'll have three options: Believe them and purge them, not believe them and purge them for smearing their own good name, or not purge them, but take a penalty for doing so.
    • Also, one of the Soviet Union's focuses allows for Stalin to become a Field Marshal^note similarly, if you do the Left Opposition, Trotsky can become a Field Marshal. While this focus is normally locked until you deal with Stalin's paranoia, if you somehow manage to complete it while Stalin's Paranoia is still active, it's entirely possible Stalin can purge himself^note before you ask, this only removes him as a field marshal - Stalin will still lead the Union.
    • Lastly, although extremely rare, some cases have been documented of Stalin purging generals belonging to other countries.
  • Another bug that was discovered after the release of No Step Back: the continuous focus Naval Production would grant players a 20% boost to dockyard output. However, it's been discovered that if you constantly start and restart the focus, it will stack, which means you can reach a production bonus in the hundreds without any tech bonuses - not only does this make it practical for Germany and France to catch up to the larger navies with just screen ships, but it also makes achievements such as My Ships don't Lie^note which requires the production of multiple capital ships and Vive la Jeune Ecole^note producing over 150 destroyers as France laughably easy.
  • One achievement for Battle for the Bosphorous ("One Nation Under Ataturk") normally would only work after you had removed the negative state modifiers...but on the patch that was released with the DLC, it was discovered that if you loaded a game as Turkey without the DLC activated, you'd get the achievement the second you started the game. This was patched, although those that earned the achievement still got to keep it.
  • When Germany capitulates France while France is part of another faction, isn't the faction leader, and the faction leader hasn't capitulated, Germany can establish Vichy France^note if this happens with a Monarchist Germany, they can establish Bourbon France instead - however, if France is able to retake Paris, Vichy France will get an event where they get to allow themselves to be annexed by France^note provided they were formed, obviously, likely to account for cases where the Allies are able to land on Europe before Vichy France is dragged in^note in the current game, one of Vichy France's focuses will generate tension, thus allowing the Allies to justify on them and get them involved, giving Free France a chance at retaking the Vichy held lands, as doing so would drag Vichy France into the war; however, if the Allies are able to retake Paris before that point, then Vichy France would not join the Axis. However, the game doesn't check if the France in possession of Paris is independent, meaning that if the player either puppets Free France and ensures they have Paris in their control, or establishes a collaboration government, then their French puppet will automatically annex Vichy France, giving the player control over all of Vichy France for free - in particular, it's much more practical for Germany to gain access to the French Navy this way than through Case Anton. And this isn't limited to Germany either - any country can do this if Vichy France was formed.
    • A variation of this bug from the early days of the game: If you played as Italy and did the focus "Demand Baleric Islands", doing so would have Nationalist Spain either agree to part with the islands or refuse. If you got the islands and then released Republican Spain as a puppet, however, doing so would cause the event that fires whenever two countries of the same ideology are at a civil war to fire off, which would cause Republican Spain to annex Nationalist Spain!
• Just Here for Godzilla: HOI4's extremely active and highly popular modding community has resulted in many players getting HOI4 just for the mods, often completely ignoring the base game.
• Low-Tier Letdown: Ever since army doctrines were introduced in II, Grand Battle Plan is consistently overshadowed by better picks, is clearly weaker than alternatives, requires some specific gimmick to shine or any combination of the three. In II and Darkest Hour it is particularly awful due to the way how research works in those. Since research is done by tech teams and they come with pre-definied specialisations, chances are if your country has a team geared for researching Grand Battle Plan doctrine, it won't have alternative doctrinal team. And researching lackluster doctrine is still better than trying to catch-up in different field without a specialist.
• Moment of Awesome:
  • Taking Berlin as Poland or Tokyo as China. Both are quite hard to do, but the special news event you get from doing so helps remind you of just how epic your counteroffensive was.
    • For an even harder challenge, try to beat Germany as Austria or Italy as Albania. It’s hard, but it will feel epic once you successfully do so.
• Memetic Badass:
  • The minor Asian country of Bhutan in HOI4 has the fascist country name of Thunder Dragon Empire. The over-the-top nature of the name led to many memeing the country as though it was a superpower.
  • Luxembourg, the weakest country in HOI4 at game start, has attracted many players looking for a challenge. There are many world conquest runs as Luxembourg out there on the internet, which has resulted in Luxembourg being memed as an extremely dangerous country in the playerbase.
• Memetic Loser:
  • Italy is mocked as one by the fanbase, due to the sheer incompetence of its AI. It is especially apparent in IV, where it does worse than it did in the real-World War 2, getting quickly ejected from North Africa, failing even worse at invading Greece, and almost inevitably failing to stop the British & US from naval invading its homeland. Italy is so bad that should anyone intervene in Ethiopia on the Ethiopian side, Italians might end up being bogged down in that war for years or even lose. Italy wound up being the last of the 7 starting majors to get a reworked focus tree, receiving theirs in By Blood Alone, after the Soviet Union got one in No Step Back. This has slowly started to change over the years with Italy now being treated as something of a Woobie for being sidelined by Paradox for years.
  • The Democratic alternate history paths for most countries are often maligned for being boring and underpowered. They’re often oriented towards being more defensive, which can remove a lot of chances for the actual meat of the game- the warfare- to play out.
• Memetic Mutation: So much, that only memes pertaining to the original game are included in this list. For mods, check their respective pages.
  • ''Tannu What?" ^note Tannu Tuva is a small socialist nation sandwiched between Mongolia and the USSR. The nation is so small and obscure that when the Soviet Union completes the focus, a global event fires saying that the small country was annexed and the only answer of the countries is Tannu what?
  • What if X won World War 1?^note The original user of this meme is the large mod Kaiserreich: Legacy of the Weltkrieg with the subtitle "What if Germany won World War 1". The popularity of Kaiserreich led to many derived mods (most of which never got past the conceptual stage) and thus derived memes, such as "What if Belgium won World War 1?", "What if Russia won World War 1?" (has it's own mod called In the Name of the Tsar), and things like "What if nobody won World War 1?" (which got its own mod called Red Flood) or "What if ISIS won World War 1?". The mod Führerreich: Legacy of the Great War is also a case of "What if the Allies won World War 1?", in a sense parodying the meme.
  • El Generico is the name used to refer to a specific generic portrait◊ used for Latin American heads of state that didn't have portraits, the problem is that most of Latin American nations didn't have any portraits and for some reason, despite having multiple generic portraits in the files, the game would ALWAYS choose El Generico, having the hilarious consequence of him leading multiple countries at the same times and when the country's ideology changed he would just change his suit or add a small hammer-and-sickle pin on the suit.
  • High Hopes: Liberia DLC, a joke regarding Paradox policy of making completely ahistorical and unbalanced focus trees for minor countries, especially if they didn't even take part in any WW2 military engagements. With the backdraft created by Mexico's focus tree announcement, the meme returned with double the force, despite it being originally created as a reaction toward the lack of balance in the (real) Death or Dishonor DLC released in 2017.
  • Komet Sighted, doubles as a Mythology Gag due to almost every Paradox game including "comet sighted"
  • The "Battle of Wuhan" track from HoI4 OST has been used as meme fodder due to the Coronavirus Disease 2019 Pandemic which originated in Wuhan.
  • The abundance of Alternate History-themed mod in general, and the fact many of them were dark settings (notably, Red Flood and The New Order: Last Days of Europe) resulted in an in-joke about the modding scene being a contest to create the most "cursed timeline".
  • A very popular way to "play" IV is for players to recreate all sorts of scenarios with mods, be it real or fictional with every faction played by the AI, before sitting back and watching the time-lapse to see which faction eventually is the winner. Jokes regarding Darkhorse Victory ran rampant with the results.
  • Italy will never get a new focus tree^note Despite various changes in the game since release and new focus trees for various countries along with reworks of existing ones, Italy is still stuck in its original, release-state tree. This even including the changes made with Spanish Civil War, and all the trees being adjusted... except for Italian one.. Became a Discredited Meme after the release of By Blood Alone, which featured a new focus tree for Italy.
  • It's a running joke in the community that no one actually understands the naval system in IV.
  • "Rate My Encirclement"^note  Many players like to show off their encirclement of enemy troops. This has even leaked to other games such as Europa Universalis, where encirclement is not a mechanic and would have been irrelevant.
• Narm: The Allied Speeches Pack became a butt of jokes immediately after announcement, partly because it charges money for a bunch of public domain speeches that people can find for free and add to the game via mods, and partly because the "Allied" word in the title only draws attention to the fact that an "Axis Speeches Pack" would never be a thing, for obvious reasons.
• The Scrappy:
  • In IV, Central and South American nations are generally mocked by the player base for a multitude of reasons:
    • No nation south of Mexico has a unique focus tree leading to very little action in the entire region.
    • They typically have very little impact on gameplay but major impact on performance as the AI will favour doing nothing but spamming units the entire time but never declaring war. El Salvador is a meme in the community for sitting on its two tiny provinces and doing nothing but creating dozens of units.
    • The terrain in the regions is primarily jungles, swamps and mountains as well as impassable regions making logistics nigh impossible, made even worse by the new logistic systems added into the game.
    • Due to the Monroe doctrine by the US if any non American nation decides to invade the hemisphere America will instantly intervene.
  • In online multiplayer games anyone who picks France and then rejects the Rhineland remilitarization will get kicked & banned because it completely ruins the game, wasting the time of everyone who was playing in it.
• Scrappy Mechanic:
  • Except for I^note Only new models of tanks, planes and ships have the familiar upgrade system that more or less builds the whole thing anew at half the price, while everything else just receiving stat bonuses directly after research is done and Darkest Hour ^note Where you have to specifically order each unit separately to do so, no other game in the series offers to directly upgrade your units to top of the line gear - you always do it step-by-step. This is particularly annoying in III, where you've got dozens upon dozens of technologies and thus statistics that each has to be upgraded separately^note For example, your infantry isn't just upgrading in general, it is keeping separate track of what tier are defensive weapons, service rifles, support gear or doctrines and how close to next tier the upgrades are, with bonus to upgrade speed for each of those also taken separately and always only one step forward. Having high technology, but the fielded army being obsolete? Tough luck, you going to spend years re-equipping those, of course assuming you've got the industrial capacity to afford that. In fact, in III, unlocking too many one-tier technologies can bog down your entire industry, since you have your entire army applying new gizmos to it, ramping up the costs of upgrades per unit and thus meaning you can't afford the general upgrades, turning the whole thing into a logistical nightmare. And units only upgrade when out of combat, so good luck with that past the 1940 mark. IV significantly retooled the whole system, since better gear to your units has to be produced first, but it is issued only when out of combat.
  • In II and thus Darkest Hour, light tanks automatically upgrade to medium ones. Unless you explicitly flag the unit to be exempt from upgrades, it will start gearing toward the lowest tier of medium tanks, which is rarely desirable. Not to mention building medium tanks directly is much cheaper and faster.
  • Naval invasions are a pain in the ass to do in IV, and are poorly explained by the game as it requires naval supremacy over the location the invasion will take place and there are some harsh restrictions on how many units you can use in the early game (which some nations requiring an easily missed technology to do it). It doesn't help that the AI is abysmal at doing them. Even if the German lead Axis smash the Soviets and control Europe, the AI is often completely incapable of winning naval supremacy over the home waters around England, resulting in a stalemate until the US enters the war at which point the US & UK can win supremacy only to throw away divisions in poorly designed naval assaults often with as little as one unit. Invasions of the USA by Japan or vice versa will also leave the player waiting years unless they do it themselves.
  • The UI element for creating air forces is dreadful in IV. Absent even a basic ability to filter the list by plane type and tier, it just lists every single individual model of aircraft in a long list which is in a very small window. In any prolonged war, you will capture dozens of different types of planes and will get thoroughly sick of scrolling through the list to find exactly which one you want. Additionally, the way air reinforcements work is that any variant or new model will automatically replace any existing deployment. This doesn't help the clutter of the UI because your list will always keep filling up with the worst models you have made as they get replaced by the new one. Paradox eventually added the ability to trash vehicles, behind a DLC paywall of course.
  • The spy/espionage mechanic in IV is generally regarded as underwhelming, if not outright useless, with the only practical operations being setting up collaborationist governments or having spies suppress resistance in occupied territory. All of the other covert operations have such negligible effects they're not even worth bothering conducting. The huge industrial and time investments required also mean only major powers will be able to set up an intelligence agency and even then, you'll be lucky if you even get one collaborationist government ready before the war kicks off.
  • At the peace treaty with happens to end a war, the number of casualties is one of the biggest contributors to the war score, the point system which determines how the defeated lands are settled. This can be very frustrating for a player that effectively done most of the work conquering the most lands with minimal casualties...only to lose most of them to another party that kept throwing their armies into a meat grinder stalemate and racking up casualties. Yeah, because that is totally how you measure the performance of a winning faction. Not to mention, if said party is your next target, this means you have to conquer the same lands again.
  • In IV, if you want to release a nation or form a Collaboration Government, you have to release all states they own...even if one of the states they own is a core of yours. Wanna release France as a puppet after forming the Holy Roman Empire so you can steal their manpower? Say goodbye to Savoy and Alsace-Lorraine. An especially annoying version of this is if the country you're trying to release gains a core on a state - if Poland annexes Germany and then gets enough compliance to form a collaboration government, if Germany did Danzig or War, Poland will lose Danzig in the process.
  • The random purges in No Step Back would be fine if it wasn't for a combination of the fact that a), the only way a general or admiral can avoid being purged is if they have Stalinist Loyalties (which can be annoying if you're going for a civil war to overthrow Stalin, as generals with said loyalties will side with Stalin when the war breaks out), and b), Stalin can even target generals who, historically, he did not purge (i.e., Georgy Zhukov, Konstantin Rokossovsky, Aleksandr Vasilevsky), even if you're playing the historical route. There's also the fact that it's entirely possible for the player to have the bad luck of having Stalin purge their entire roster of generals, meaning that you have to waste command power to generate new ones - which wouldn't be so bad if it wasn't for the fact that the high command now requires command power in addition to political power. For that matter, if you go for the Right Opposition, you had better hope that he doesn't randomly purge Alexei Rykov or Nikolai Bukharin, because if he does, then a good chunk of that path is locked out^note the Left Opposition can send its leaders and advisors into exile, thus allowing them to avoid being purged.
  • The Stalin Paranoia mechanic being introduced really bought to a head complaints & arguments in the fanbase about Paradox stuffing the game full of what the community call "mini-games" where you have to manage esoteric country specific mechanics that do away with the regular way of managing your country. These include certain civil wars having you build support per province, border conflicts, the US congressional politics mechanic that no-one else in the game uses, Turkish, Dutch & Greek investment decisions, the Chinese warlords and the Bulgaria focus tree, or the Italian, Ethiopian and Swiss balance of power mechanics.
  • Any country that has a focus tree without a single 35-day focus, because it's such a chore to work your way through it, especially if you're basically on a time limit and another country will usually declare war on you by 1938. The worst offenders of this are probably Yugoslavia, whose focus tree is confusing on top of all this, and France, of all countries, because its' focus tree has so many individual paths to go down
  • The additional guarantees that Paradox added to the game make early wars as smaller non-democratic powers much harder to do, as you bring down the full weight of factions on you rather than a limit war between two nations.
  • In IV, peace conferences in single player are widely loathed due to the AI almost always releasing or puppeting nations, even when it makes no sense to do so. IE, the British always release Occitania, even though it's a core part of France. This tends to create "border gore" all over the place and usually interferes with what the player wants to do. It's not unusual for World War III to start just because players can't stand the ugly borders created by the AI.
• Self-Imposed Challenge: There are plenty of nations that are much weaker than the major powers the player can play as and try to beat the historical odds.
• Surprisingly Improved Sequel: The first game was a very basic reskin of Europa Universalis and was pretty meh, along with similar critical reception, and was quickly discontinued from support. It wasn't until II that the series really found its niche and all the mechanics were polished, providing important details and room for any meaningful modding. Effect? An entire bunch of mods, with Darkest Hour being eventually released as its own game and loyal playerbase to justify the rest of the series.
• Suspiciously Similar Song: The Allies' themes in III and IV are rather similar to the main theme of Band of Brothers.
• They Changed It, Now It Sucks!: Numerous elements of gameplay were completely retooled with 4th game, with really mixed reception, to say at least:
  • Garrison and militia battalions were completely removed from the game, forcing players to design their own rear guards from costly infantry or unsuitable cavalry. While it's not problematic by itself, it can quickly get simply annoying to manage - especially if it might end up costing precious army experience to even design such units in the first place. Garrisons were put back into the game for La Resistance, while Militia units can be vaguely designed by setting up Infantry units that have no support companies.
  • As of the 1.5.3 patch, Artillery regiments have been repeatably nerfed, so much so that the original strategy of using 14INF:4ART or 7INF:2ART^note  14 infantry and 4 artillery or 7 Infantry and 2 artillery respectively in as a division template is no longer a viable strategy in an attempt to make players experiment with other designs and micro-manage their troops on the front line. But since it's still the best set up for infantry divisions, all it achieved was a half-hearted nerf amid a massive outrage. On higher difficulties, the nerf does bite though, as attempting to make such big artillery-heavy divisions will often cause massive supply problems down the line.
• Unexpected Character:
  • While it's hard to call any country existing unexpected, few if any people would have expected Mexico to get a focus tree in a naval focused DLC, or under any circumstances get one before Belgium, Spain, or Scandinavia, but in large part due to bordering the USA, which was part of the main focus, Mexico also got a focus tree in Man the Guns.
  • Repeated in the La Resistance DLC, with both Portugal and the Spanish receiving reworks, when it was expected that the Soviets would get a much-needed buff/rework^note To put this in perspective, the Soviet Union has not had their focus tree reworked since the release of IV (until No Step Back, the seventh major DLC), meaning the Dutch, Spanish, Manchu, Mexican and Portuguese have received more attention. Portugal is an especially weird choice, as it stayed intentionally neutral throughout most of the war and unlike Mexico, doesn't even offer any sort of counter-balance mechanically.
  • Repeated again in the Battle for the Bosporus DLC, which adds content for Turkey, Greece, and Bulgaria (respectively a neutral country, a minor Allies member, and a minor Axis member).
  • While the Soviet Union and Poland were expected to get reworks in No Step Back, the Baltic states (which largely did little aside from being annexed by the USSR) getting focus trees as part of said DLC was not, given that many expected Finland to receive a focus tree instead.
  • By Blood Alone continued this trend - while Italy's rework was guaranteed, and Ethiopia had been predicted by some, the third nation in the pack was Switzerland, which is famous for its policy of absolute neutrality - many fans expected Austria or Albania to round out this trio, given that their role in the game on historical is not that different from Czechoslovakia, which did get a focus tree.
  • Not only can Wojtek the Bear^note a Syrian brown bear who was adopted in 1942 by Polish soldiers while they were stationed in Iran, and was officially enlisted as a soldier in an artillery supply company. He notably took part in the Battle of Monte Cassino be promoted as a commander for Poland, but the No Step Back DLC adds him as one of the claimants for the throne of Poland!

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