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HOI4 Dev Diary - Combat and Stats changes

Hi everyone and welcome back to another dev diary! Today is about various changes that affect combat and units. With the Barbarossa update we want to shake up the meta a bit and also change a few stats and other aspects to make using the tank designer more interesting and rewarding.

High Command bonus changes
For a long time now unit bonuses from high command have confused people. Most expect that they apply to battalions, when in fact they apply only if their target unit type was “the majority type”, which was basically a weighted type count. They also could overlap, so infantry, mountaineers and artillery would apply to the same units letting you stack stuff in ways that was never intended and quite unintuitive.


This system has now changed, and divisions get bonuses based on their composition, this is a straight up ratio based on the number of non-support battalions of each type, so a 2x artillery 3x infantry division will be 40% artillery 60% infantry.
Battalions are always classified as a single type for this (even though some are scripted with multiple types) based on this priority:
cavalry > armor > artillery > motorized > mechanized > infantry

The exceptions being rocket & special forces, which both act as an addition, so if the 3 infantry divisions in the example above were mountain units, then the division would also be 60% special forces and if the 2 artillery are nebelwerfers it'd also be 40% rocket

When counting the battalions of armies (ie when we have an actual unit and not only a division template), battalions that lack equipment will count as less, so a Light Tank battalion with only half it's tanks will count as 0.5 battalions (and not count at all if without tanks). The total sum of the compositions will still end up 100% (unless every battalion is without equipment).


To make it easier to see this we now have an indicator in the division windows showing the breakdown.

Combat Width
As a part of our efforts to shake up the 40/20 width meta, we have made changes to the combat width of province terrain. Province widths now range from 75 to 96. Plains have a new base combat width of 90, while Mountains have a new combat width of 75. Most of these widths will not divide into each other easily, hopefully moving the ideal width away from multiples of 10.

Urban provinces are now the “widest” with a width of 96. But this does not mean they will be the easiest provinces to overwhelm. Mountains, marshes, and urban provinces now have reinforcement widths of ⅓ of province width instead of ½. This should hopefully give these provinces a slight defensive buff, while allowing us to open up pushing power in the more open tiles.


In conjunction with these changes, we have also been looking at reducing the overstacking penalty. We hope that this will alleviate some of the need to have divisions that are the perfect width for a given province. But at the same time, smaller countries should now be able to specialize their division width to suit their home terrain more appropriately.

Breakdown (numbers not final etc etc)
  • Plains
    • Standard 90
    • Reinforce 45
  • Desert
    • Standard 90
    • Reinforce 45
  • Forest
    • Standard 84
    • Reinforce 42
  • Jungle
    • Standard 84
    • Reinforce 42
  • Hills
    • Standard 80
    • Reinforce 40
  • Marsh
    • Standard 78
    • Reinforce 26
  • Urban
    • Standard 96
    • Reinforce.32
  • Mountain
    • Standard 75
    • Reinforce 25
One of the major things that make larger divisions like 40 width armor hit disproportionally harder than smaller ones is also how targeting and damage works inside combat in relation to the enemies defense. Essentially the larger divisions make more efficient use of concentrated damage as it punches through defense. To solve this we are doing a few things. First of all we are weighting the targeting towards wider divisions being more likely targets and also when picking targets to try and match it to have wider divisions spread damage over smaller rather than always concentrating it. They will probably still hit harder, but combined with width changes and other downsides of larger divisions it should make it less clear cut.
However, this part isn’t quite done yet though so I’ll cover it again in more detail in one of the “bag of tricks” diaries in the future when i see how it pans out, but I figured it needed to be mentioned now ;) That said though, to wet your appetites here is a little tease from a debug mapmode in development...

Armor and Piercing
Currently the effects of having stronger armor than the enemy can pierce, or being able to pierce an enemies armor are binary and give fixed bonuses. This meant that there wasn't really any benefit to have more armor than you needed to stop the enemies piercing, and also that being a single point of piercing under enemy armor was just as bad as having no piercing. So things were quite binary. With the tank designer coming we wanted to make it feel like your investments in upgrades were always worth it, so we are changing armor and piercing to have more gradual effects.

Armor > Piercing
  • Unit takes half damage (as it currently works)
Armor < Piercing and Amor > 0.75 * Piercing
  • Take damage between half damage to normal damage by difference in value
Armor < 0.75 * Piercing
  • The unit takes normal damage
Lets break this down with an example:
  • A panzer division has an armor value of 52
  • Its being attacked by an infantry division with some anti-tank guns. Their piercing is 60
  • If this was the old system this armor would be worthless and not reduce damage at all
  • Now because its close enough (between 60 and 45), so you get roughly half of the normal effect around 25% reduction of damage.

For the tank designer it was important that reliability was more impactful if it was to be a good tradeoff with other aspects of design, so we needed to change it up (lest @CraniumMuppets 0% reliability tank monsters would take over the world). Now it will not just affect rate of loss in attrition but various other aspects:
  • Reliability affects losses from attrition like before
  • Reliability now affects org regain when moving, and also makes any weather related org effects more impactful when low
  • Lower reliability scales up all impacts from weather so if facing extreme weather a unit with low reliability equipment will suffer more of those weather effects
  • At the end of combat units with better reliability will be able to get back a certain amount of tanks etc to simulate that simple more reliable constructions would work better for battlefield repair and be less fragile when taking damage. So it's a bit like capturing enemy equipment in combat - but in reverse :cool:


Our goal is that this creates interesting tradeoffs when designing equipment and will make you have to consider if its worth switching a strategy focused on speed and firepower towards reliability when operating in bad weather and tough areas like the Russian winter or in northern africa or jungles.

Oh, and I figured now might be a good time to point out that there will be a future diary on weather changes and other cool related stuff, so these changes aren't completely in isolation. But one step at a time :)

But before we go, a few words about the studio...

Studio Gold
Hello everyone, my name is Thomas, but perhaps better known as @Besuchov here :)

As you saw here we have recently reorganized ourselves a little, moving from a big centralized Stockholm studio to splitting ourselves into Red, Green and Gold. This is mainly an internal org shift to make sure we keep our growing organization firmly focused around making good games. You shouldn't notice too many differences in the short term, we are still PDS making GSG on the Clausewitz engine, but it does mean that we can align each studio to the particular games. Since you will hear the studio names every once in a while, I just wanted to say who I am and what the studio is responsible for.

My role is Studio Manager, which means I'm accountable for the long term success of Studio Gold and working with things like management, staffing, and long term plans. Studio Gold has as its main focus Hearts of Iron (but we may or may not have some secret other stuff as well). Directly making the games though, that's still the job of Podcat and the team, but I intend to do my best to create an environment where we have the best chances to make great games together.

For me this is coming full circle at Paradox. I started as a programmer in 2004 and one of my first tasks was to work on Hearts of Iron 2. Since then I've done various things including being lead programmer for Hearts of Iron 3 (and Victoria 2), Project Lead for EU4 and more recently Studio Manager for PDS. Next to EU, HOI is my favorite game and I'm delighted to be back in a place where I can focus on fewer games and where that game is Hearts of Iron. You will see more of me in the future even though I will mostly take a backseat to the team working on the game.

That’s all, see you all again next week for more dev diary goodness!
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On time. Now reading the dev diary.

Thanks, Dan.
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Let's break the meta! I hardly understand it anyway!

I personally love the idea that we're busting open the old strats and assumptions about optimization. It demands innovation.

I hardly understood anything in this diary, since I much prefer playing the actually game and not crunching every number possible, so I suppose I am thrilled! I feel liberated I get to tackle a new system that encourages taking new risks and breaking away from the tried and true 10/20/40w
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How is the AI at handling these changes, and will we ever see a dev diary on that?
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Sounds exciting. Really hope this encourages more experimentation with division templates and equipment types. Previously there wasn't really any incentive to try anything unique since 20 width infantry and 40 width tanks did the job just fine but these changes (specifically armor and combat width changes) have the potential to shake the meta up a bit.
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Hi Podcat,
since you are Game Lead i would like to copy one last time a heavily upvoted post from past diarys with an easy to implement suggestion.

I have a suggestion for all focus trees.
Please mark the "historical" path in the focus tree somehow, so that as a player i can jump in as any nation and when i open the focus tree, i can see what focuses to take in what order for a historical game. I think the best way to do this would be to just highlight the focuses taken by the AI in historical mode and the order they are taken in.

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