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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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Entry for giveaway:

It would be interesting to see French Indochina become its own thing like what happened to the Belgian Congo-opening up the possibility for a Ho Chi Minh led revolt to liberate Southeast Asia from European and Japanese interests. This could tie in with perhaps a bit of post-war content for France which would allow them to fight an Indochina War like how they did in our timeline after WW2.

Also if Paradox really wants to add post-war content, then I would recommend adding a small focus tree and/or event chain for the breakdown of the Chinese United Front after the defeat of Japan and the second phase of the Chinese Civil War kicking up, maybe with added peace out option for the Nationalists to flee to Taiwan if they fail.

Finally, naval invasions require a rework especially since this upcoming DLC will likely be focused on the Pacific Theatre and increasing the importance of island hopping beyond just the Philippines and Taiwan. My recommendation is to make the naval invasions work similarly to the raids from Götterdammerung, having a chance of success that fluctuates based on the naval and air supremacy instead of the current arbitrary 50% naval supremacy system which in constantly infuriating.
 
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With the upcoming DLC reworking another major power, are there any plans to further integrate some of the older DLC into the base game? In particular, I believe some of the features from Man the Guns, like the Ship Designer, being implemented in the base game would create a much more solid foundation on which a Pacific War focused DLC can expand upon, as well as making the game more accessible.

Also, the more DLCs you have, higher the chance of focus tree conflicts. Imagine if Paradox didn't integrate Waking the Tiger into the base game, we would have potentially 2 distinct DLCs reworking China! Some speculate that a US-focused DLC would not be far from now, which conflicts with Man the Guns, since that DLC also adds new branches to the USA.

As a new player, I believe integrating the first 3 DLCs into the base game was a huge boon for the game and would like to see more of that going forward.
 
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I think it's a good idea to implement air defense towers as a new special project, as the Germans did especially in Berlin. Also a good addition could be the giant glider project or gliders in general that require having researched basic transport aircraft. I also think that certain technologies that are under-researched should be moved to special projects, such as night vision technology of any kind. I also think torpedo boat technology should be available to unlock within the naval branch of special projects.
 
It would be fun to have something else than complete anexation after each war ngl haha, EU4 peace deals although aimed for longer gameplay, are class, something to learn from there
 
oh man i wanted so bad an update of south east asia for sooo long i'm so hyped to see this one coming, i mean i really like to play japan but if i want more gameplay with it i have to play with a mod but i always prefer to play the vanilla game instead of some mods and seeing the update coming soon i'm ready to buy it already
 
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I frequently play the USA and I would welcome an update or refresh of the Pacific War. Aside getting drawn into the war 6 or 7 months early when Japan declares on the Philippines in April or May '41, once I can counter or neutralize Japan's two big fleets, gobbling up all the Pacific Islands only takes as long as the "Preparing naval invasion" counter takes to tick down. So any further depth Paradox could provide to that theater to spice it up would be amazing. Also, a China rework might be enough to finally try them out. I've been initrigued, but watching that slog as I march across the Pacific has daunted me thus far. With developments in making defensive wars more engaging, I think China would make for a good slow-burn playstyle.

From the "things I'm still learning about the game" file, I just learned in the past few months that the reason my mid-44 US navy was trying to sail on fumes was because the level 4 port in San Francisco was supplying 70% of the Pacific, including the major operational areas. Clearly I don't quite understand the logistics logic, because I figured they'd route through the level 10 in San Diego. Anyway, I've now noted the problem and managed to fix it in my latest round.

Speaking of not understanding parts of the game, the Base Strike doctrine gives a bonus to carriers when engaging submarines (detection and something), but when I put escort carriers (converted cruiser hulls) in ASW groups, I get a warning about fuel inefficiency or something. I thought that's what they're supposed to do?

And if I could make a request, I'd like some more flexibility from the Naval missions categories. As a specific example, a strike force that is waiting for an enemy fleet to enter a region it is covering, might also sail out and support (CAS and/or bombardment) any naval invasion missions in it's covered zones. The supporting role would be secondary to hitting enemy fleets, but even then, the strike fleet would have an improved response time to any fleet seeking to interdict the invasion.
 
I imagine they'll announce mid- to late next week, at the earliest. It's the weekend, so no one's looking at anything until Monday. There's probably a small team who will divide all the comments by their respective days, and then do several passes to whittle down the number of comments to the desired 30, and they have to do that 5 times.

Best case scenario, the people involved will get a couple days dedicated to sorting that out, but I think it would be more likely that everyone involved has regular duties they still need to address, and so it may be largely done via group chats and intermittent meetings over numerous days.

I wouldn't sweat it for at least a couple weeks.
 
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