HoI4 Dev Diary - Officer Corps Recap & AI Improvements

  • We have updated our Community Code of Conduct. Please read through the new rules for the forum that are an integral part of Paradox Interactive’s User Agreement.
Showing developer posts only. Show all posts in this thread.


Game Director - Hearts of Iron
Paradox Staff
Feb 13, 2018
Hi all, and welcome back to today’s developer diary!

It can be very easy to get super-focused on details when looking at individual systems or parts of features - something we often tend to do when writing developer diaries. Each week, we’re going to give you an overview of a core system that we’ve so far introduced in parts, and will include all of the changes we’ve made to that system over the course of development, since we first looked at it.

In addition to this, we’ll also take a look at some changes coming to the AI in No Step Back, so if that’s more your jam, feel free to skip to the end ;D

We’ll begin with an overview of the Officer Corps:


This image represents a near-final take on what the office corps screen will look like.

As you can see, the branch chiefs, theorist, and military high command have found their way to the officer corps screen, though for ease of access you may still view and appoint them in the country overview screen like before. This kind of change is the sort of thing that comes up during playtesting - while it made sense to collect similar things together, there was no good reason to change the player’s flow expectations.

The manner in which you’ll appoint advisors has changed a bit. We decided during the officer corps development process, to make a bigger deal out of the advisor ‘level’ (specialist, expert, genius) that all non-theorist advisors possess. In addition to adding a flat command power allocation (reduction of max command power) which is reduced by high advisor ranks, political power costs are raised by having a higher rank advisor.

Branch advisors now grant daily experience gain, meaning stacking your command cadre well is vitally important to the pre-war development of your military. To add to the choices, doctrines now cost experience rather than being something you spend a research line on:


For owners of No Step Back, military branches also possess several specialization options in the form of Military Spirits, which are also unlocked with experience:


We found during development that less was more when it came to creating a tightly balanced set of choices, and we’ve limited the number of options in each category to around six, with each category being strongly themed around Academy, Military Service, and Command.

To add slightly more nuance to choices here, we ensured that several options in each category would be made available based on situational factors - ideology, doctrine branch, and in rare cases, country choice, can all make new choices available.

The most important part of cultivating a strong officer corps, is the ability to give your trusted commanders advisory roles. Commander traits earned in active combat can make your characters eligible for specific advisory roles:


Characters promoted to advisory duties this way will continue to advance their advisory rank as their commander level increases - a highly experienced field commander will grow from specialist to genius over the course of their career.

Lastly, we are introducing the preferred tactics weighting system. This allows you to set a national, field marshal, and commander-level preferred tactic, which will weight the chances of picking said tactic in a combat situation. While the national preferred tactic can be switched out for a cost, selecting a preferred tactic for your commanders and field marshals is something that remains a permanent choice, representing their adherence to a particular doctrinal theory.

Of course, a host of minor changes accompany the officer corps, including new alerts, better resource tooltips, and adding some of this information into intel ledgers for opponent countries.

The AI

And now, on to a topic that is sure not to evoke strong opinions from anybody here: the AI.

During the development of La Resistance, work was begun on adding additional tools through an imgui that allow modders and users to see various internal data. In NSB, a significant amount of time was spent adding to this tooling and providing support for future AI development, as well as laying the groundwork for easier iteration on AI behaviour and more.


One of our new in-game tools for assessing AI font priorities. These tools will be available for modders, who can continue to fine-tune AI for their own needs through the use of strategies and defines. Here, you can see that the AI has evaluated the topmost defense order as desiring a minimum of 7 divisions, an 'ideal' count of 8, and a maximum count of 50. Defense orders tend to fluctuate quite heavily in 'ideal' unit counts: they tend to be quite elastic to make up for units not needed elsewhere.

While much of the work done here was investment for the future, we’ve also made some pretty big changes to the way the AI evaluates where it commits its troops and more.

While it can be hard to indicate objective improvements in terms of AI, there are several key areas we aimed to improve for this release:

Use of specialized divisions - the AI for assigning armor and special forces to appropriate fronts has received some improvement. The practical upshot of this means you ought to see fewer armor divisions assigned to inappropriate orders (garrisons, pure defensive lines etc), and mountaineers used in frontlines that have the right terrain types.


Did I mention the AI likes tanks?

Unit weight distribution - combined with the new supply system, the AI evaluation of where to put units has been totally overhauled. In practical terms, this is likely to manifest as seeing the AI commit more troops to defend key areas (ports & coasts), care more about the active supply situation on frontlines, and provide something slightly resembling a defense in depth for their own core territory, even during active frontline pushes elsewhere.


You can see that the AI considers supply carefully when assessing front unit distribution. There are certain circumstances in which the logical supply capacity of a front can be exceeded by the AI - notably when a defensive frontline is facing a numerically superior foe, or when the AI determines that it needs to win a war fast.


Once Moscow has fallen, the supply situation can get pretty dire as you push east.

Naval Invasions - logic for AI naval invasions has seen significant improvement. You should be encountering larger, less frequent naval invasions overall. The Ai will try to take advantage of weak points in coastal defences, and generally be more keen to invade to support theaters. This got so scary we had to turn the new capabilities down several times (of course, these can be tuned back up).

Counters - while it can be difficult to determine a ‘right’ time to switch templates or create a specialized template, we’ve improved logic for majors utilizing specialized divisions such as Tank Destroyers in relevant circumstances. You should see the AI care a little more about what you throw at it.

Buffer Fronts - Several AI strategies now involve the use of buffer fronts. These are specially defined area defense orders which will request a proportion of national divisions to man them. Where these differ from regular garrison orders, is that these fronts will ‘loan’ their unit distribution counts to nearby fronts or invasion orders.

For example, the heatmap below show the distribution of US troops several months prior to Overlord. The troops stationed in Alexandria and the UK are using buffer fronts, which will supply frontlines in europe, in order to avoid having to relocate troops from much further away. Here you can see the (somewhat anachronistic) defense of Greek territory being supplied by the buffer front in Alexandria, which is in turn supplied with divisions from the US mainland (arriving through the Mediterranean).


The locations and weightings of these are instructional only.
  • 195Like
  • 77Love
  • 10
  • 8
  • 2
  • 1Haha


Game Director - Hearts of Iron
Paradox Staff
Feb 13, 2018
Shouldnt the ai determine that it needs to win every war as fast as possible?

Not really. Consider it like aggressiveness settings / the faster you push, the more careless or expensive orders might be.

Any changes to the yellow exclamation mark that causes front lines to freeze? many atime this has resulted in divisions not reacting or moving at all leading to easy encirclments and gaps in the front line

You can override this with order execution settings. 'Aggressive' will ignore supply status for movement, balanced will take some care, and careful will act as before.

My test for the AI is going to be if UK AI is finally gonna keep a garrison on their isles at all times instead of leaving it undefended or only a skeleton garrison which happens like 90% of the time.

This was a bug actually, which we have fixed.

I saw in the polish playthrough dev diary that :
1) AI wasn't actively prioritising railways defense (Caucasus screenshot, 7 divisions defending Rostov, 30 divisions fighting in Caucasus mountains)
2) AI wasn't evacuating by sea low supplied encircled coastal pockets

Questions after today :
3) Can we have more details on those defense orders?
4) Is there any change to tank usage other than front allocation priority?
5) How is the AI dealing with variable terrain combat width?

1. Unlikely to change, it is not trivial to work out when this is a good idea (computationally). In addition, logistics defense orders require an enormous number of divisions outside of specific situations.

2. No change here. You still need a port.

5. Not sure what you mean. There's always been rudimentary handling of frontage. The AI has updated templates to account for some terrain width changes.

I really hope buffer fronts means the end of empty Egypt and British Isles because the UK likes to ferry it's troops all over the world

Yep, that's the idea.

Love the new changes to the AI especially the increased weighting of AI defending ports and supply centers. Some questions considering this the AI DD,

In your guys and gals test runs with NSB, how has Russia been doing against the Axis? Is it starting to (on historical) consistently start to push the Axis harder?

Still undergoing work, but things are broadly looking good.

Has the Japanese AI been reworked to not, or limit, its invasions of India on historical. Especially considering that they'll often have a land route via Vietnam and Laos. (Naval invasions of Burma are fine and historical, its just annoying to see the India, Australia, and New Zealand all capitulate on historical).

I try and steer away from outright banning AI from doing certain things. If a player US decides not to invest in the pacific theater, for example, I would expect Japan to run wild there for longer. Where a player is involved, you can't expect things to turn out historically, and railroading them to do so just makes situations that deviate from what is expected, look even weirder.

How have the Allies been handling the supply changes, especially around D-day and other naval invasions. This tends to be their fatal weakness RN, so some comments on this would be helpful.

Currently they overstack frontlines a little, but no more than they can handle. Floating harbors help their initial invasions considerably. One important factor here is that we've tried to normalize being low on supply, a bit. Where previously low supply penalties were quite binary, there's a lot more scaling based on supply status now.

Has AI Spam been addressed at all with the current changes?

Define AI Spam?
  • 34
  • 28Like
  • 1Love


Game Director - Hearts of Iron
Paradox Staff
Feb 13, 2018
Hi, sadly I think that developers are gone by now, but let me still ask, how much maximum command power will I be left with, if I get a whole genius level high command? Cause it would be pretty sad if I have to decide between good high command and using force attack for example.

Approx 90-120 depending on other factors.
  • 24
  • 4Like
  • 1Love


Game Director - Hearts of Iron
Paradox Staff
Feb 13, 2018
Have you considered adding a soft division cap like Kaiserreich does to prevent excessive endgame lag caused by the hundreds of divisions in game?

There is one.

Is coordination a division level feature, could a modder make tanks have higher than normal coordination, or a coordination support company like how signals give initiative?

What exactly is required to level up a general's advisor buffs? Do any level 5 generals always become experts or do they need to gain new levels to upgrade?

Coordination is not a division level statistic, but is affected by initiative when applied in combat.

Advisor levels are linked purely to the general's level. 4/6/8 for Specialist/Expert/Genius, I think.
  • 28
  • 4Like
  • 1Love