* AwesomeArt: The [[https://www.youtube.com/watch?v=WEN5SEb5ASA pre-order trailer]]. Unlike other trailers which use stock images and footage, this one features awesome Soviet propaganda styled artwork.
* BrokenBase:
** The announcement that IV would only have about three political parties angered most of the community as it was seen as a major step backwards from the 10 parties you had in [=HoI 3=], though some Paradox fans are fine with it.
** 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 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 as historical accuracy as possible. Due to this, Paradox Games added Manchukuo through a patch in IV.
* GameBreaker: Now with [[GameBreaker/HeartsOfIron their own page]]
* GoodBadBugs: One patch for Darkest Hour had instances where after the Soviet Union lost a war against the axis and accepting the bitter peace event, [[UsefulNotes/VladimirLenin 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}}
* MagikarpPower: Nationalist China starts out with abysmal units and research teams and a non-existent navy, but has plenty of IC. If you play your cards right, you can turn it around and turn China into a formidable nation not to be messed with.
* RescuedFromTheScrappyHeap: Initial reaction to introduction of mana mechanics from [[VideoGame/EuropaUniversalis Europa Universalis IV]] was greeted with collective groan from the [=HoI=] community. Turns out experience is gained in organic and controllable way, while also playing relatively marginal role in the game.
* ScrappyMechanic: Planning, introduced in ''IV''. Instead of manually commanding all your army, you can provide your units with battle order and plans for the entire conflict, preparing in advance all the positions, how to guard them, where to retreat, where create pockets for encirclement and destruction and so on. In reality, the battle planner tool is so crude and just plain inefficient at creating plans, it can take more time and cause much more trouble and than manually giving orders to, say, entire German land forces for taking over Soviet Union up to Urals. Planning is suppose to provide combat bonus when units are executing the plan, but it's so small it has almost zero impact on the actual combat. Fortunatelly, planning can be completely ignored... [[ThisIsGonnaSuck unless you want to conduct amphibious assault]].
* SuspiciouslySimilarSong: The Allies' themes in ''[[https://www.youtube.com/watch?v=tPUpRBmcuOo&index=5&list=PLB55FF169BD130E9E III]]'' and ''[[https://www.youtube.com/watch?v=7ITkwsycObs#t=01m03s IV]]'' are rather similar to the main [[https://www.youtube.com/watch?v=7uTAIpU0sa0b theme]] of ''Series/BandOfBrothers''.
* TheyChangedItNowItSucks: Numerous elements of gameplay were completely retooled with 4th game, with really mixed reception, to say at least:
** Removal of supplies is considered as a ''massive'' step-down within the community, especially after ''III'' and then its mods went into extreme lenght to at least try to model all the issues about logistics. ''IV'' instead applies arcade mode, where all the game calculates is how many weapons are are fielded versus the required number, doing extremely arbitrary decisions when and if there is even any loss of equipment. [[EasyLogistics Local infrastructure, terrain, size of ports and alike have absolutely zero impact on anything]].
** Garrison and militia batallions 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.
** The way how air combat is handled, managed and.... well, let's just say air combat in ''IV'' simply sucks. Instead of creating actual units and giving them missions, there is ill-applied counter that calculates nominal strenght of units over given area and the game resolve combat and missions based on it. Thus having vast technological superiority and having your airforce staffed to the brim with [[AcePilot aces]] can end up with complete and utter failure, even if enemy is still using biplanes, just because completely arbitrary number is applied.
*** It's especially painful, because on paper, all the elements building the new mechanics behind airforce and air combat should provide extremely fun and detailed simulation. Instead, numerical superiority, even if minor, seems to be the only real factor, disregarding everything else.
** Good god, amphibious assault. It takes massive planning, forcing player to use the otherwise ignored mechanics, takes entire weeks to prepare and all you have to do is give order for your units and ''just wait'', doing nothing. Also, it can be completely and utterly destroyed on open sea if you happen to encounter a single enemy ship.
** Complete removal of command structure and replacing it with Generals and Marshals. Any country having half-decent general can instantly promote him to Marshal and then proceed to use ''single commander'' for the entire armed forces. It can break the game to almost unfun level, while players are ''encouraged'' to do so. Also, due to changed command structure, AI is utterly helpless at commanding own forces and properly staffing all the fronts, since it tends to use the same guy to command units on three different ''war theatres''.
** Naval combat was considerably simplified from ''III'', returning to the infamous tactic of "fastest average speed wins". You see, it doesn't really matter how powerful your battleships are, how many naval bombers are on your carriers and how precise your radars are. Everything is decided by average speed of entire fleet, so sometimes a difference of 0.01 can decide entire battle. And it can be achieved by just spamming cheap, fast-to-build destroyers, which then can turn entire carrier battle group into shreds at no cost and almost no loses. This often cause unrealistic outcomes, like Kriegsmarine (scripted to focus on destroyers and submarines, both really quick) utterly destroying Royal Navy, which uses powerful, but slow battleships and heavy cruisers (and most of them are outdated anyway, which makes them even slower)
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