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Hearts of Iron IV Anniversary Week & Developer Corners!

Generals!

Not only is our nine year anniversary happening today, but we've got a lot of content for you all to read through so make sure to continue reading. We've got Developer Corners starting up again, HOI4 Anniversary Giveaways every day and the Multiplayer Mayhem happening in the 2025 Community Cup!


But first, a word from our Commander in Chief @Arheo .


Greetings all,

As the oft-quoted Eisenhower stated, ”In preparing for battle, I have always found that plans are useless, but planning is indispensable”. In the spirit of this, we thought it would be time to take a look at the long-term roadmap for Hearts of Iron. It has been around three years since our last formal Hearts of Iron Roadmap, and while plans have changed and evolved, this statement of intent has been largely what has guided our development process up until the release of Götterdämmerung.

Our mainline intended innovations, when this was written just after No Step Back, included the following:
  • Improvements to Frontline Stability (Progress in NSB, more to come)
  • Strategic and Tactical AI improvements
  • Battle Planner Improvements
Götterdämmerung included a lot of improvements to the AI including Force Concentration: a feature designed to simulate tactical pushes and armor concentration. This has been an interesting one: when released, we saw a lot of players taken by surprise by the AI using this approach, and a lot more discussion over players being defeated or losing to the new AI behaviour. However, most of the community seems to have adapted fairly quickly to this change. To me this is a positive thing: while having a broad playerbase with varying levels of skill means we need to be gradual about how and if we increase overall difficulty when playing against AI, the existence of community “meta” and learning materials gives most players tools to catch up. In short, there’s no reason not to continue iterating on AI features that may increase average difficulty or required skill levels.

On a related note, we’ve fixed a bunch of issues with frontline stability, but battle planning remains a tool that has a stark divide between how new and veteran players utilize it. We’ve done some quite deep user research into this particular area, but this resulted in few actionable results beyond handling edge cases better and improving frontline integrity.


Long Term Goals and Strategies to guide AI (Progress in NSB)

Most of this is “under the hood”, but we’ve made a lot of progress adding tooling to interpret and direct how the AI performs long-term planning. This area of the game is notoriously opaque and it’s taken a fair while to get to the point where we have enough analytical insight into the mechanical decision-making process of the AI, but, we’re more or less there now. This has meant improved tooling such as AI strategies, imgui debug tools that modders also have access to, and better integration with existing mechanics that previously existed “on top” of the game without interacting much with the AI. This is of course a goal that has no defined end-point, but compared to where we were three years ago, much has improved.


Improving Peace Conferences

By Blood Alone saw a contribution-based peace conference system added, with numerous narrative demand options. On reflection the design approach here was not super stable, and while the feature hit most of the key notes (contesting demands, earning defined contribution, rewarding better play), it fell into a similar trap to the old system when it came to AI antagonism. It took longer than it should have done for that behaviour to stabilize with tweaks and changes, but we’re in a better (if not perfect) situation now.


Update Core National Focus Trees with Alt-History paths alongside more Options

We’ve had a couple of methods of doing this. First are the maintenance updates included in some War Effort patches. These tend to be quite minor, but we’ve added a fair few things to various focus trees over time.

Secondly, revisiting focus trees such as Germany and Hungary represents a greater investment into this. Overall, I’m happy with the dual-pronged approach to this; reworking focus trees comprehensively is a full expansion-cycle affair, and doing it outside of a paid release is not something we will ever be able to do. I feel the majority of the community understand this, and our roll-in approach to DoD, TfV and WtT has been for the most part welcomed.


Great Power Diplomacy

I’ve spoken at length on this in a few other places. Fundamentally, design ideas for this one always ended up conflicting with focus trees. HoI4 is a war simulation with a superimposed latch-driven state-machine that drives the global narrative. It is unlikely we’ll change that approach. However, the process of working through design ideas for this has given us some avenues for further exploration.


Multiplayer & Social layer Improvements & Support

The Career Profile and associated features hit the social layer note pretty well. Traditionally, these features are designed to increase player engagement: something which HoI doesn’t really have an issue with. However, the feature has proven to be unexpectedly popular amongst specific groups within the community, both for completionists and as a learning aid. While I don’t think we’ll be making any fundamental additions to this, it won’t be going away and we’ll keep adding content such as new medals and ribbons.


Economic Decision Making

We haven’t made any great strides here. We still have medium to long term plans to expand the industrial economy elements of HoI, while taking care to avoid simulating too many pure economic elements.

Special Projects

Götterdämmerung represents the culmination of this project. I’m pretty happy with how this turned out, though now that we’ve had some time to monitor the wider effects of special projects, it is about time to revisit balance and take a pass on the huge array of tech that was added in the Götterdämmerung update.


More Difference between sub-ideologies & Government forms, Advisors and Internal Politics Improvements

We didn’t really get here! This is quite a difficult topic to broach in a strategy game, and other things ended up taking precedence. We’ve had some minor changes to advisors, but nothing to write home about in the grand scheme of things.


More National Focus Trees

Fairly Self-explanatory.


Make Defensive Warfare more fun

This is still a goal of mine, but we haven’t managed to tackle it yet. I think some of the fundamentals of HoI4 (ie, stuff we simply can’t/won’t change) stand in the way of doing this justice, though it also plays hand-in-hand with changes to doctrine and division design which are definitely in the works.


Adding Mechanics to limit the size of your Standing Army, Particularly post-war etc

Definitely still planned, though not a major priority on its own - will have some words on this later. I don’t feel like this is something that has been glaringly missing for a game with a narrative of “crescendo to war”, though as we start to experiment around the fringes of that pillar (smaller regionally-focused conflicts and expansions), it will become more necessary.


Have Doctrines more strongly affect Division Designing

We’ve had some success here with the changes to support companies and equipment streamlining. I wouldn’t go so far as to say this is “done”, though. We have short-medium term plans regarding doctrines though, and having them affect division design more strongly is one of the key pillars for this effort.


Immersion and Roleplay Elements, Optional tools for making your mark in a game

We’ve added a lot of things that touch on this: division medals, plan naming, deeper recruitment design, MIOs and industrial specialization being chief among them, feature-wise. I think these features do what they set out to do: letting you leave your own mark on the battlefield and the campaign narrative. As you may have noticed from recent war effort patches, we’ve also identified that we need to be better with streamlining how players interact with these types of features.


War Effort Updates

I talked at length in the 2022 roadmap about the introduction of maintenance updates - something we ended up doing, and calling “War Effort” patches. On their own merit, these have been extremely useful for us, and have allowed us to iterate and introduce quite a lot of system updates and quality of life changes such as:
  • Persistent equipment designs
  • System Rebalances to designer modules and units
  • MIO streamlining
  • Some quite significant performance improvements
  • Over 1000 bugfixes
  • Mod support
  • Focus tree updates
  • Balance standardization of some systems (quite important for game health!)
One of the things we were uncertain of before we started War Effort patches was whether this would reduce the maintenance included in major updates, resulting in effectively just moving things around. With the exception of our approach to country packs (ie; not including maintenance updates at country pack release), it has not directly affected the size and impact of major releases.

The old Roadmap championed these as a method of updating older focus tree content. It’s fair to mention that this ended up not being a major focus of war effort updates. It became quickly apparent that developing focus trees is the majority of the work our Content Designers do; that’s not realistically something we can do in iterative updates.

So while there is success here, there’s also room for improvement. We will keep producing War Effort updates, but I want to try and find some form of structure to them, and a way of steering them in a way that more quickly addresses high impact community issues. Particularly, I would like to find a way to increase the visibility of our approach to handling community issues, though I will caution that this will require some time to achieve.


Next Steps

Aaand that’s our retrospective.

That ended up quite a lot longer than I’d expected, but that’s ok - the future plans are at least a little more concise! I want to give you an updated roadmap for our next few years, though with the usual caveats. As you can see above, these plans are not super specific, they aren’t promises, and they don’t always work out. Nonetheless, the act of planning is extremely important, and communicating those plans perhaps even more so.

So what does the future look like for HoI4?

It will come as little surprise that South/East Asia is next, with content primarily focused on Japan and China, and mechanics to support this narrative, as well as reinvigorating the Pacific war. I don’t want to go into too many specifics here (tune in next time for more!), but the war in and around Asia as well as the Pacific has been left behind by our recent developments directed at the European elements of the conflict. To give some broad strokes here, we’re looking at developing the narratives that faction membership will give you, improving and streamlining elements of naval control, with a particular focus on the types of naval warfare that carried the Pacific conflict, and adding much greater strategic narrative (and a less opaque simulation) to the flow of naval conflict. This is not an exclusive list, and it’ll probably leave you guessing - but you won’t have to wait long.

In the longer term, we have some other areas that we’re keen to take a pass on:


Military Doctrines and Division Design

These systems are quite old and don’t offer much ability to shape your gameplay. I would like to link these better, in order to have doctrines shape both how you compose and how you use your military.

Manufacturing and Industrial/Economic Gameplay

Watch this space.


Breaking the Snowball!

HoI’s “crescendo to war” that I mentioned earlier is extremely important to the main narrative of the war. However, as time goes on we have released more content focusing on the smaller players in this conflict. There are elements of the game that don’t mesh particularly well here, and I want to take a look at the way wars and war escalation are structured to make this more engaging and less disruptive when minor conflicts erupt.


Improving the Diplomatic Landscape

“But you said you couldn’t do this!”, I hear you cry. And mostly you would be right. However, with the introduction of late game technologies in Götterdämmerung, there is even more reason to continue playing after the end of the war. I would like to keep developing how the world “falls out” after the conflict, producing more realistic geopolitical results as well as the potential for new and more systems-driven “what if” conflicts after the end of the war. Of course, any such changes would be multiplied in effect if they could also touch upon the pre-war landscape too…


Alt-History

Well, that’s a broad category. This is one we’ve been looking at in quite a lot of detail. We see an increasingly stark divide within different groups of the community on how we (or even if we should) approach alt-history. For those that enjoy it, don’t worry, we’re not going to stop making alt-history content, however, I have asked the team to look, in the long-term, into ways of producing more structured, plausible alt-history content with clearer historically-adjacent narrative hooks. In addition, we have started to evaluate if it’s possible to create more deterministic global alt-history situations and produce some “semi-alt-history” ways of playing HoI - something that I think would capture the fun parts of the non-historical content we provide while also retaining the benefits of the determinism that the historical scenario imparts.

I have one, final note on the practical elements of what we release. We intend to continue releasing what we’ve previously termed “Country packs” and “Unit packs”, but we need to both be clearer about what is or isn’t included, and adjust the scope. We’re devoting some more resources to our Country pack development moving forwards, and we’ll be including mechanics and systemic changes in those the same way as expansions - albeit still focusing on “minor players” in the war.

Alright, I started writing this three hours ago and apparently I’m still going, so here I will force myself to stop. I’m here to answer questions.

/Arheo


Hearts of Iron IV Dev Corners 2025 Roadmap - Updated: June 16

Of course, these dates may be subject to change so keep that in mind!


Hearts of Iron IV's 9th Anniversary!

As apart of HOI IV's Ninth anniversary, we've decided to do another giveaway with a different prize each day including some fan favourites and some keys for the new Song pack for those of you who missed out on some of those banger tunes. To participate and enter for a chance to win some of these codes, make sure to reply here on each day you want to take part in the giveaway.

Because of time zones, we've decided that each giveaway "day" will start at 14:00 CEST, so for example, if you want to take part in the Bonus Songs Pack giveaway on Tuesday, then you need to reply between 14:00 CEST on Tuesday and 13:59 CEST on Wednesday. If you reply on Wednesday 14:00 CEST, then you're taking part in the Wednesday giveaway, etc.

You can reply as many times as you want, on as many days as you want, but if we're looking through replies and have to choose between two replies, we will probably choose the reply that has some substance (vs "Just replying to take part") so be creative, engage, comment on the announcement or on others' replies.
(Giveaway T&C attached below)

Today: HOI IV Starter Edition So you can play with more friends x30
Tomorrow: Bonus Songs Pack To listen to, even when you're paused x30
Wednesday: No Step Back To bring Communism to the world x30
Thursday: By Blood Alone Take your fight to the skies x30
Friday: Arms Against Tyranny To bring the fight to the Nordics x30

Hearts of Iron IV Anniversary Sale!

To add even more fun to our anniversary celebration, the Hearts of Iron Sale (up to 70% off) is now live over on paradox.com!

Community Cup 2025

We are back for yet another round of the Community Cup, hosted by Dankus. This year, the Teams are participating for a chance to win 5000 Euros! With Casters such as Dankus themselves, Mo and one of our own Community Ambassadors Fraser, the finals will be played June 7th at 17:00 CEST.

Make sure to catch all of the action over on Dankus's Channel, or the HOI Youtube Channel!
 

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I've said it somewhere here before, but they really need to revisit the older trees and change all the "70 days for 1 factory" focuses.
Luckily we're getting that soon with the new DLC (I hope). I've been playing China recently and I think I can count the amount of 35 day focuses with the fingers of one hando_O (pain)
 
It's incredible that after so many years, this game has continued to receive an updates and improvements and DLC to continue to make it as fun, no, even more fun, then when this game was fresh and new! I'm very excited about the announced planned improvements and tweaks, especially a Japan rework, and the attention that's being given to late game playability! I've always found it kind of game breaking, after the snowball, how the reality is of economics are completely thrown out the window, as Zerg hoards of troops are thrown onto the lines, with complete disregard for the economic realities of fielding such a force. I know, I've got a temper my expectations and be careful what I wish for, because sometimes tweaks and balances have potential to become nerfs and exploits, but that's all part of the fun, too!
 
I'm very excited for the new stuff coming for especially Japan and China as I have always felt like the Japan focus tree was missing the scope a major focus tree has nowadays and for China, there is really not that much to do after the war with Japan concludes. That being said, I hope the state of the warlords and the guerilla warfare is more explored than it has been already.
These next coming months are gonna be great with all the transparency you guys put on. I will try my best to make sure I'll not miss a single Developer Corner. The June 19 entry sound a lot like we're gonna get some more information about how to DLC will shape the preparation and execution of naval invasions, great to see!
Glad to see this continued support and love for the game years after! o7
 
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I'm here once again with another idea. This one is related to production, and partially navy.

So you know how for naval warfare you want a certain ratio of different kinds of ships to ensure maximum screening efficiency (and I don't think we are moving from that design away completely). But it can be tough figuring out how many dockyards need to be assigned to each class. So I've been thinking, what if each dockyard simply gave you a certain amount of IC points that would all go into one pool. Then we would use some kind of novel interface, where we would assign out desired ratio of different classes of ships, and the game would automatically assign those IC points to different production lines in a way that results in a navy of desired ratio. This could also integrate warnings when we would have too few heavy ships to screen carriers, or too few light ships to screen heavy ships.

Something similar could also apply to mils. For instance, by default military factories would produce equipment in ratios that our divisions utilize, but we could adjust those when we want to expand our air force, or plan to train some more armored divisions.

This could also potentially enable some more variety with lower number of mils or dockyards. Some minor country with 1 or 2 mils probably cannot afford to make anything other than rifles. But with such system, they could say they want to end up with this many rifles to this many cannons, and the IC points will be assigned accordingly. Heck, they could even produce a third (or however many) type of equipment if they wanted to just with those two mils. Of course, you may still want to prioritize, because the overall production rate is still going to be slow, and you may not have enough stuff in stockpile to train your basic divisions if you diversify too much.
 
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for China, there is really not that much to do after the war with Japan concludes.
Resolve the civil war and unite China? Implement democracy? Spread control over SEA? I'm not sure what more you're looking for, because there's usually not much in the way of post-war content short of going WC. Especially with Nationalist China, which historically got kicked off the mainland.
 
You know that France focus tree upgrade requires le Resistance to become free dlc… not gonna happen for at least 10 years, because le resistance is so new DLC!
Small tweaks… maybe …
I'm also not particularly optimistic to see major changes towards the French focus tree...but if it is touched again, than IMHO the first thing which needs to go is the complete reset of the big focus tree after completing the Vichy/Free France minitree... I know that people don't like 70d focii for meager gains (and I don't like them either)...but...isn't it even worse to have to do those weak focii all over again (for the same little or even no gain at all) to further progress?
 
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Happy Anniversary dear Hoi4ers, what a journey it has been, and it's not even close to being over yet, can't wait for what's coming next (and can't wait to see Morocco, Egypt and Tunisia represented on the map as protectorates as they should be (including the Tangier international zone lol) with proper content, hopefully soon), as for the giveaway i would love to get the AAT dlc but my luck is non-existant, just like Mohammed V portrait lol, have a blessed day and good luck to everyone <3
 
Do wonder as my final remark about the Manufacturing and Industrial/Economic idea is how resource-limited countries would have been producing basic infantry and support equipment - whether notable arms exporters like Czecho-Slovakia would have been worried in a wartime scenario about native metal extraction being insufficient with a need to supplement with potentially imports that later may not be available due to being in conflict (certainly in the game one in spite of the nation's limitations in the number of factories that can be built it can still set enough production to exceed available iron), or if the aluminium or rubber situation exactly had such an impact on policymaking as is represented ingame with sacrificing an entire civilian factory (or for rubber a building slot) to import/synthesise for a limited number of truck factories etc.

Although harking back to my previous post probably almost entirely a problem off the back of not always being able to balance out the civs cost for importing with the civs you gain from exporting.
 
Since navy getting reworked i would like to see maybe some change to spys too and their interaction with navy. New missions that can be onboard of the ships? Maybe the actual submarine that the mission says to be a real one or something like that. Would be really to infaltrate inside enemy ships. Like a double agent trait being able to infaltrate the army/navy/air would be very cool!
 
Entry for Giveaway, Happy 9th Birthday.

It's hard for me to write about Nordics, I didn't play them too much, I can only say something about waging war against them or having them as an ally, most of my experience with Sweden is from Vicky and the EU.
I didn't even play Finland more than twice, and both times it was in R56, but I want to sell weapons, and I want a designer for my designers.

The most experience I had with Nordic nations was with Norway and Finland and Denmark. First is Finland, I actually never concured it as Soviet Union, In hindsight I could have done it many times but, I always felt a bit of fear when sending troops to the front, I remember all those documentaries I watched about winter war, or just hearing Sabaton singing about heroes of the winter war, about Talvisota. I had 2 playthroughs as Finland in Road to 56, one was more successful than the other, at first I didn't really know what to do, and ended up building a strong industry only to get invaded through the Mannerheim line. The secon time where I focused much more on the military, and had two light tank divisions, the Soviets didn't bother showing up, so I just kinda took Leningrad, and managed to fortify. I held for about 6 moths before I started getting overwhelmed, and my front started collapsing due to lack of manpower. I don't remember what happened after that.

But I did play Sweedin a bit more, although in EU and Vicky 2, I had a lot of fun as Sweden, creating my big empire marching through Baltic whilst carolean prayer plays, only to somehow end up with Karelia instead of Baltics and a rival of Hungary and Ottomans instead of Norway, Denmark and Lithuania. I also had a lot of fun in Victoria, trying to create your own empire in the North to get Finland and Baltics, without becoming rival with Germany, only to backstab them in what is essentially a world war 4. Or you somehow manage to end up with chain of islands somewhere on the map, which you got as a reparation from the British and Portugese because you managed to catch some of their convoys escorted by one expensive ship at the time, but since you didn't really pay attention you don't know what you got.

I tried playing Sweden in HoI4 too, but with a generic tree it's not the same. I tried making Sweden into an empire, but I ended up starting ww2 a year earlier, or if I try to build up, I end up not having enough manpower, and I end up playing general simulator, where I essentially control an army somewhere in Germany.

I would love to experience AAT focuses, especially sweeden, and norway since I herd that Norway has some wacky naval focuses, I also wanted to try and build up a naval contender with Iceland, and most importantly I wanted to become war proffiter as some random nation like Czechoslovakia or Yugoslavia, not even to mention USA, and I also want to experience MIOs, I want to feel that even if I am not doing anything meaningful at the time in air research, my engeners are constantly tunning the engines, they are figuring out what positions for guns are most effective, they are reshaping wings, and tail, they are figuring what parts need to be more protected, they are figuring out how to cut production expenses, how to streamline the process, how to save resources, I don't want to have my fighter design chance once every 3 years, same goes for every other piece of military equipment.
 
I hope i can get the Arms against Tyranny DLC, i've got a few dlcs that i bought recently but i lack by blood alone and arms against tyranny so if i can gain it, I'd be really happy, Happy 9th anniversary Hearts of Iron 4, I enjoyed playing alot.