Hearts of Iron 4 Dev Diaries

Dev Diary 1 Our Vision What is Hearts of Iron?

In light of our recent successes like Crusader Kings II and Europa Universalis IV, I realize that we

probably have a lot of new faces with us - people might not have tried the earlier Hearts of Iron

games. So, before we dig into what makes Hearts of Iron IV different and special, let me talk a bit

about what the series is all about so that everyone has some grounding. The Hearts of Iron series is

about taking control of your nation of choice in the years around World War II (1936 to 1948) and

leading it to victory. And it all comes down to how well you, as a player, can navigate your ship of

state - that is your supreme weapon. Hearts of Iron IV is the wargame where a high level of strategic

and military planning is needed for you to secure victory. Every action you take has the potential to

tip the balance of power in your favor, forever altering the political and ideological landscape.

A WWII Grand strategy game

Hearts of Iron is, like most Paradox Development Studio titles, a grand strategy game in an open

sandbox. The World War II theme does mean that there is a lot greater focus on the preparation for

war, your industrial output and military doctrines and equipment. But in Hearts of Iron IV, you are

dealing with the bigger picture and a very high level of strategic planning; this is not a pure old-

fashioned wargame. Losing small battles is utterly insignificant to the larger campaign. You have to

look at the entire war and take decisions in a multiple of aspects to reach victory - this is truly high

level war planning, including production lines, technological advances, securing strategic resources

and, of course, making those large armored drives through the plains of Europe.

Comparison to other PDS titles

The big thing that sets it apart from our other game series such as Crusader Kings II and Europa

Universalis IV is that it covers a much shorter period of time, namely the years around the Second

World War and that it focuses heavily on preparing for and fighting that war. This means that your

priorities will largely stay the same throughout the game your are unlikely to make a dramatic

change from one kind of nation to another. You can pick any nation in the world and either ride out

the storm on the sidelines, get involved in the grand cataclysm, or try something a little bit in-

between. Hearts of Iron is packed full of historical flavor and awesome details, something much

harder to accomplish in games spanning hundreds of years.

However even if Hearts of Iron IV is a grand strategy game highly focused on war, the role you take

on as the player is close to the role you take in Europa Universalis IV - you will play as the guiding

spirit behind the nation trying to shape history and determine the fate of your country, often guided

by in-game events and decisions. The game focuses on making choices for your nation, both in

warfare as in the character of your countrys technological progress, national ideas and strategic

goals. You can pick any nation and decide what role you will take in WW2.

You can choose different play styles depending on your personal interest or based on the different

strengths and weaknesses of the historic powers. For example, as Germany you have an incentive to

start the war, while the UK and US will likely start on the defensive and will fight massive naval

battles. You can even try to survive as a minor nation, whose government continues fighting from

exile or be a smaller power taking advantage of the global war to expand your rightful territory.

Nothing that says that your goal must be to win WWII - since the game is sandbox, victory is

determined by the goals you set up for yourself during the WWII time-span.

http://www.heartsofiron4.com/http://www.heartsofiron4.com/http://www.heartsofiron4.com/http://www.heartsofiron4.com/http://www.heartsofiron4.com/http://www.heartsofiron4.com/http://www.heartsofiron4.com/http://www.heartsofiron4.com/

Hearts of Iron IV Development Diaries (STRG Click PIC-Links!) 1-11

http://www.heartsofiron4.com/

Vision

Our goal for Hearts of Iron IV is to do something similar to what we did with Crusader King II and

Europa Universalis IV - keep the flavor and complexity of the game intact while making the game

much more streamlined and easier to learn, with much improved interfaces. We also aim for a fresh

playing experience so there will be changes from the previous game.

More focus on planning and high level decisions.

Hearts of Iron III could either be played with full manual control, where micromanagement would be

pretty heavy (often to the point where you would struggle to pay attention to all aspects of the

game) or with AI assistance, where your control over the systems you surrendered to the AI was very

limited. We are developing a planning system that gives you greater control while not being as taxing

as the detailed manual play from the last Hearts of Iron game. We want to give you time to look at

the bigger picture. In my opinion, this also adds a lot of immersion, since it feels more like I am

guiding a military campaign rather just shuffling units between provinces.

For the micro-managers out there - you can still do very detailed plans and update them in real-time,

which will basically work like the old manual control but the system will reward successful longer

term plans, so expect to have a few things to learn! There won't be any large "automate this"

buttons in the game. We want all parts to be fun and playable. If they are not, they get redesigned or

replaced.

Less railroading more historical feel

A big problem with historical games is that people know what happened, especially in such a well-

documented period as World War II. The leaders of those days did not have crystal balls or an active

forum of amateur historians from the future telling them what would happen next. This is something

that we need to deal with without losing the sense of place and realism that people have come to

appreciate about our games. A lot of things will require gradual changes and actually living through

events, which should give a much better historical feel as well as creating a game where it is easier to

try out alternate paths of history and not feel that the only road to success is following whatever plan

Eisenhower had.

Everything at your fingertips

To play Hearts of Iron you need a lot of information so you can make the right choices, be it long

term (where is the best area for my armored spearhead?) or short term (what time does the sun

set?). Previously this required you to look around in a lot of places - in Hearts of Iron IV information is

much more context sensitive, and most important stuff will be shown directly on the map. You will

see more of this in future developer diaries.

To sum it up:

Our hopes for this game is that you as a player will feel in control of a real global conflict and want to

learn the tools of warfare in an open sandbox environment during this intense period of history. Our

goal with Hearts of Iron IV is to create a WWII game completely focused on Global Strategic Warfare.

We are aiming to make Hearts of Iron IV the best WWII strategy game yet with a smoother learning

curve and deeper gameplay. Its pretty ambitious, but I think we have the experience and passion to

pull it off. And the recent experience of Paradox developed games shows that were on the right

path, I think.




Of course, actual development for Hearts of Iron IV hasn't been going on for that long yet (we are

currently in pre-alpha), even if we have been thinking about it and discussing it for years. As we

designed each expansion for Hearts of Iron III, there were always things too large to implement, or

that wouldn't quite fit into the world, and we had to put those things in our "future" pile. So when

starting development we had a few years of notes and discussions to go through. I expect old beta

testers and forum regulars to go, "Ohh, I remember this!", as we start to reveal new things in diaries.

We will start slow and release development diaries about once every month and later speed up their

release as we march towards early 2015 so sit back and enjoy the ride!

Oh, I almost forgot! Here is a screenshot of the map (click for larger version). This shows just the

terrain currently. It is early and political borders are not yet polished to be accurate enough to show

them off. Enjoy!




Dev Diary 2 The Tools of War Today, I am going dive right into the meaty stuff and present one of the larger changes we've made

to the game - equipment. It's a broad topic with many implications for how the rest of the game is

played, so my goal is to present the general idea without digging into all the details just yet. But don't

worry, there will be more details than you can shake a field-marshal's baton at in future diaries!

Production

We wanted a more interesting industry model that offered a compelling reason not to always use the

latest technology, as well as adding more unit flavor in HoI4. To accomplish this we developed a

model where you no longer build full divisions and aircraft wings one at a time; instead, you create

production lines to pump out individual vehicles. The longer you run a single production line the

more efficient it gets at producing that piece of equipment, and the choice of when to switch over to,

say, a newer tank model becomes tricky. Is the war effort best served by a shiny new Tiger that can

outclass the competition, or would you rather have 20 Panzer IVs? You will have to make choices like

this. Upgrading your equipment now means replacing your old models at the front with new tank

designs, for example. The old ones can be put in reserve, sent to less important places, or perhaps

given as aid to an ally.

This means that a division is basically an assortment of different equipment combined with men who

operate them. Most of the stats of a division will come from equipment, so a panzer division without

tanks will not be particularly fit for duty. As for exactly what equipment is used by each division, it

will depend on how you have structured your divisions. At the smallest level, we are looking at

battalion types that make up your divisions determining how much you need of everything, but a

division is still the smallest unit that can be moved around the map. For example, adding an extra

battalion of artillery to a division means that it will now also require a few more men and a specific

number of artillery cannons that you will need to produce before that battalion will be effective.

Well talk more about this in a later diary.

Technology

Equipment appears all through the new technology trees. The idea is that unlocking a new piece of

equipment should be very visible, and it should be very clear what you will get. Here is a screenshot

showing what the armored tech tree looks like for Germany:




Armored technology is based around chassis that you unlock. Each of the chassis has 4 subtechs,

each of which unlocks a variant. So, for example, once you have unlocked the Panzer III tank you can

research the tank destroyer variant, StuG III. The StuG III was a Panzer III chassis with the turret

removed and a larger fixed gun placed in its stead. Variants like this can be switched to production

lines from the original chassis without much of penalty, so once the Panzer IV becomes your main

tank and the Panzer III no longer measures up, it's a perfect time to convert to producing StuGs on

those Panzer III lines. Most nations developed their vehicles like this during the war, and we wanted

to include this flavor. Historically, the StuG III ended up being the most produced armored vehicle in

Germany during the war.

There will also be ways to create more custom equipment variants with abilities unlocked by

experience over the course of the war. This is also something we will go into more detail on in the

future.

By switching to equipment from HoI3's more abstracted model, we gain a lot of cool flavor as well as

introducing many of the actual interesting choices that leaders of the time had to deal with. We also

believe it will make it easier to understand for new players, as well as being more immersive for

players. You will now see results like "10 heavy tanks destroyed" rather than some abstracted

strength percentage. Because the production models changes over to lines it also doesn't introduce

any more unnecessary micro management, so it is really a win-win.

+ Bonus read: Hearts of Iron IV: How we changed the world

Time to flex your strategic muscles and test your might as your ability to lead your nation will be the

ultimate weapon in your arsenal in Hearts of Iron IV.

On the battlefields, in the factories, and at the negotiating table. Victory at all costs.

Here are a few of the women from the World War II era and how they changed the world:

http://forum.paradoxplaza.com/forum/showthread.php?760924-Hearts-of-Iron-IV-How-we-

changed-the-world




Dev Diary 3 - Bringing WWII to the mainstream (april fools) One of our main goals with HoI 4 has been to simplify things to appeal to a more mainstream

audience without sacrificing historical appeal. Initially this seemed impossible until the recent release

of Call of Duty: Ghosts. The key to the success of Ghosts was the inclusion of Riley, a dog companion

and playable character. Immediately the solution was clear: Popular games have dogs, and as

everyone knows Hitler was famously a dog-lover, so the National Dog concept was born.

The National Dog(ND) system should be familiar to anyone who has played CK2 or EUIII/IV, as it is

used in a similar manner to a Councillor, National Focus, or Agent from those games. You can

monitor and control your ND from the Dog Management screen by selecting a Canine Power and

then clicking on the appropriate area of the map or UI. You ND can be used for many missions,

including:

Puppy Socialisation: By allowing the political elite of your national to play with your National Dog

you win their hearts and unite them behind your cause, improving your National Unity.

Not one step bark: Your ND can be placed in a province where a defensive battle is taking place and

will prevent units from retreating by growling threateningly at any unit attempting it.

Fetch Claim: If you are simply throwing sticks for your National Dog to fetch by the border to another

country it is hardly your fault if one accidentally crosses the border and your ND follows it. However,

any territory where your ND stands is sovereign land of your nation, resulting in a valid cause for war

to retake it.

Ruff and ready research: Assigning your ND to a particular tech screen results in a increased research

speed in that field by barking at any scientists who appear to be slacking off.




Every nation has a unique National Dog, which grant a special bonus when not employed on the

above missions, some examples include:

Germany - German Shepard Dog. Passive bonus: Schutzhund. Coups are less likely to succeed.

Britain - English Bulldog. Passive bonus: Nodding. The constant nodding of this Dog's head makes

visiting ambassadors feel they are being agreed with. Their good mood results in a relations bonus.

France - French Poodle. Passive bonus: Fluffy. Has a fine, white coat.

USSR - Siberian Husky. Passive bonus: Anti-tank dogs. All units gain bonus Hard Attack.

Japan - Shiba Inu. Passive bonus: Coins. Greatly increases your income as cash appears from

seemingly nowhere.

In order to ensure players feel a genuine connection to their National Dog we are taking extensive

motion-capture footage of all dogs to be modelled so that they move and react in a realistic fashion

ingame.

Next week we'll talk about our DLC policy, but as a sneakpeak I can reveal that we noted the outcry

after the previous diary revealed that Horses will not be tracked in HoI IV. While this initially

surprised us, and we don't think it's for everyone, we are committed to listening to our fans, and so

we are proud to announce that the HoI IV Horse Armour DLC will be available on release day:




Dev Diary 4 Land Doctrines It's time for another Hearts of Iron 4 Developer Diary, and this one is about Land Doctrines. For HoI4,

we are leaning more towards the Doctrine paths you may remember from HoI2 than the mix-and-

match of HoI3. We have 4 main mutually exclusive Doctrine paths which nations can research. Each

path also has one or more mutually exclusive choices to further differentiate the doctrines and sub-

doctrines. Because we are still pre-alpha, I can't really describe exactly what each tech in the tree

does at the moment; this can and will change as we implement, test and iterate over them. I can

describe the general idea behind each path and choice so hopefully you will understand what we are

aiming for.

Mobile Warfare: This path focuses on mobile mechanized units and is the default German path.

Armour and motorized/mechanized units will have the largest gains in this path. It also reduces the

planning time needed before you can launch an attack. This path is somewhat frontloaded with early

bonuses. The first branching in this tree allows you to choose between Mobile Infantry or Armour as

your main focus. While Mobile Infantry isn't as effective in combat, it is cheaper and can be used in

greater numbers, so it could be an alternate strategy for Germany, or be used by a less industrially

powerful nation. The second split offers the choice between switching over to a defensive posture

(maximizing Manpower gains) as Germany historically did, or continuing to develop offensive mobile

doctrines. And yes, we know Blitzkrieg wasn't a formal doctrine, but the mishmash of innovations

and new techniques that the Germans used is popularly known as such, so we roll with it.

Superior Firepower: This is the American default path. This doctrine focuses on big, well-equipped,

but expensive divisions and gains a bonus when fighting in areas with friendly air superiority. The first

split offers the choice between adding more support units to each division, or focusing on

independently deployed support brigades. The second split will let you pick between Airland battle

(for increased cooperation with the air force for combat support) or Shock and Awe (which keeps the

majority of your focus on ground-based firepower).




Grand Battleplan: This could be thought of as the traditional doctrine path, and is the default choice

for Britain, France, Italy, and Japan. This doctrine path gives you larger planning bonuses and boosts

Infantry and Artillery. It is a bit weak on the offence to begin with, but has some defensive bonuses.

The split offers the choice between increased offensive potential and steadily improving all unit types

with the Assault path, or focusing heavily on Infantry with the more frontloaded Infiltration path.

Mass Assault: The default doctrine for the USSR and China. It focuses on using large amounts of

Manpower and offers increased morale and reinforce-speed. The early techs give some defensive

bonuses and Infantry/Militia boosts. The first path decision here offers either continuing with the

same methods with Mass Mobilisation (the mass use of Infantry and Militia) or adopting the

innovative Soviet Deep Battle doctrine, which makes use of the modern tools of war and boosts the

capability of Armour, artillery, and mobile units. You may notice from the image that the Mass

Mobilisation path is shorter than the others. This is because it's more of a series of stopgap measures

for nations in dire straits than a real doctrine, and we want to encourage nations to swap out of it

when/if their situation improves.

"Swap out of it?" I hear you say. Yes, you can change your Doctrine path if you want. This will come

at a cost. There will be a period of disorganisation for your army based on how far into your previous

path you were and on the size of your army, so it's likely not something you want to do when things

are going very poorly in the middle of a war. However, you do not necessarily start from scratch in

your new Doctrine path: Several techs are shared between the paths, and if you switch to a path

which includes a shared tech you have already researched you will start at that point in the new tree.




Dev Diary 5 Production Lines It's time for another Hearts of Iron IV Developer Diary, and this time I'm going to talk a bit more

about production; specifically the Production Lines and How Things Get Built. All military equipment

is made on Production Lines in HoI IV, so players will need to be familiar with how they work if they

want to maximize their war machine.

But before we can talk about the production lines themselves, we should cover how Industry has

changed in HoI IV.

First of all, we have separated industry in Hearts of Iron IV into 3 types:

Civilian industry - Used both for "Consumer goods" and building infrastructure and other buildings.

Dockyards Used for building ships.

Military factories - Used for production of military equipment such as tanks, weapons and airplanes.

This kind of separation allows us to balance different countries' industrial strengths (the capacity to

make ships is not the same as the capacity to make luxuries), and gives the player a more interesting

selection of targets for strategic bombing.

Moving on to the actual means of Production, Factories no longer need Metal/Energy/Rare Materials

to run. Requiring the player to gather several different types of resources in order to manage

factories did not necessarily add anything interesting to the mix. Being short on any of them had the

same effect no matter what you were lacking (your Industrial Capacity would shrink) and it didn't

entirely make sense that you couldn't build things like Militia if you didn't have access to Rare

Materials.

We have simplified the inputs to "Raw materials" which factories use to run. Raw materials act as a

limit on your total Industrial Capacity. However that is not the whole Production story. Equipment

also has a Strategic Resource cost, without which it takes much longer to produce. Strategic

Resources are not accumulated in pools. Instead, they represent the potential flow of resources into

your factories. For example if you have 10 Iron you can be building stuff that costs up to 10 Iron at

any one time.

A Production Line is a standing order for a factory or group of factories to make a certain piece of

equipment. Each piece of equipment has an IC (Industrial Capacity) cost and a Resource cost. The IC

cost determines how much equipment each factory can produce per week, while the Resource cost

determines how many resources are needed for the line to operate at full speed.

As a totally made up example: An Advanced Medium Tank may cost 2 IC and require 1 Iron and 1

Tungsten. Each Factory produces 10 IC, so if you assigned 1 Factory to this Production Line, you

would produce 5 Advanced Medium Tanks per week. If you assign 10 factories you would get 50

tanks/week. At the same time you would need to have 5 Iron and 5 Tungsten in the first case, and 50

Iron and 50 Tungsten in the second. (Again, these numbers are all purely made up, focus on the idea

and not the values here.) You can only assign up to 15 Factories to any given Production Line, so you

won't be able to build, say, a Battleship in one week by assigning 100 Factories to build it.




Also, do note that simply building Equipment is not the same as training and equipping a unit, but

we'll cover that in a future dev diary.

Production Lines also have an Efficiency value which affects how much value you get out of your IC at

a factory. Your efficiency starts out fairly low but increases as items are produced - slowly at first to

represent the retooling of the factories, then it begins to increase at a linear rate until tapering off

after a certain value (an S curve). You can change what a Production line produces, of course, and

this normally means all your Efficiency is lost, however there are some exceptions. If you change to a

modified version of the same equipment (for example, the same tank but with a larger gun) you keep

most of your Efficiency. If you switch to another variant of the same chassis (e.g. you switch from Pz

IIIs to StuG IIIs) you keep half your Efficiency. And if you switch within the same family (e.g. Basic

Medium Tank to Improved Medium Tank) you keep a small part of your Efficiency.

Efficiency means that you will be able to produce more once your factories are humming along. So

long as you can keep your workers on task and supplied with what they need, you will be able to

have assembly line production that properly reflects the might of an economy dedicated to the war

effort.

Our larger hope is that Production Lines and efficiency will offer players some interesting choices

when it comes to deciding what to build. Should you go for a large number of weapons you can

already churn out, or take a short term hit on production in favor of making a smaller number of

higher quality ones? Sure, your new T-43 tank is better than the T-34, but is it really enough of an

improvement to lose much of your Production Line's Efficiency when you switch over? Your PzIII tank

may be obsolete, but perhaps instead of canceling their production entirely you could convert the

Line to make Tank Destroyers or Self-Propelled Artillery on the PzIII chassis. Preserving efficiency in

some of your factories could lead to a more diverse and interesting combination of units, and allow

you to discover some parts of the game you might have ignored if you just constantly upgraded.




Dev Diary 6 Division Design Today I'm going to talk about the new Division Designer we're making. In a Hearts of Iron game, you

spend a lot of time with your Division, and being able to customise them gave it a personal touch -

You're not just using any Infantry Division, you're using your patented Infantry/Tank

Destroyer/Artillery combination which makes them winning a battle all the more satisfying.

For those who don't remember, let's recap how it worked in HoI3: There, any time you made a

division you mixed and matched 2-5 Brigade types to create a Division. While you had to research a

tech to use 5 Brigades and the Combined arms system in Their Finest Hour gave you bonuses for

using a variety of types, there was no limitations on what you could do. This meant that players could

use their knowledge of WWII and game mechanics to instantly re-organise their army along the

optimum lines for their situation. More importantly, any time you wanted to change your Division

makeup you had to deploy new Brigades and rearrange them into your divisions, it was a lot of

clicking! For HoI 4 we want to keep the idea of customising your Divisions, but make it both harder to

jump right to the optimum setup and easier to carry out your changes.

So, what's new? The key thing now is that you do not design each Division, you design a Division

Template per type of Division you want to use and then build copies of that Template. If you decide

to change your Division Template you will be told how much Equipment and Manpower it will cost

(or return, you might make your units smaller or swap, say, Anti-Tank guns for Tank Destroyers, etc.)

to upgrade all Divisions and then all your Divisions will start upgrading to the new design, subject to

things like having enough Equipment and Divisions being in supply and not in combat.

A Division Template is made up of Brigades which are made up of Battalions, this is represented by a

grid of cells in 6 columns of 5 rows with each column being a Brigade and each cell being a Battalion -

With the exception that the left-most column are Support Units of varying sizes. Support Units are

different in that they either lend useful abilities such, as an improved reconnaissance ability, or

powerful direct or indirect fire to your frontline troops.

If you can build a type of Division, you have access to a basic/historical Division Template, and you

can customise it using Land Combat Experience. You can use Experience to swap out Battalions, or

unlock either new Brigades or Battalions, but you cannot simply optimise your division makeup on

day 1. Despite the name, you earn a little Land Combat Experience even while at peace, but the

primary gain is from combat. The rate of gain depends on the proportion of your units in combat, the

more of your units that are fighting, the faster you gain Experience. This also means that smaller

nations do not necessarily earn less than larger nations, as it's not the total number of units that

matters, and large nations will likely not get much Experience when rolling over small ones.

Certain techs can give you a Combined arms bonus from combining certain unit types within a

Division, when you unlock these techs you may simply enjoy more powerful Divisions, but

alternatively you may want to down-size those divisions and re-use the returned Equipment to outfit

more Divisions of approximately the same combat power as your units before you researched the

tech.

The division design screen also gives you an overview of your divisions expected performance in

different terrain, so in the example above the tracked vehicles will give it a movement advantage in

deserts, but penalties on river crossings despite fielding engineers because of the heavy vehicles.




You can, if you wish, have multiple Division Templates for a given type, for example perhaps you

want a Line Infantry Division to be you main frontline unit, and a Heavy Infantry Division type to

assault heavily defended areas. You can copy and split off Templates as much as you want, however

you must buy upgrades for each Template separately so having too many will limit the customization

possible for each type.




Dev Diary 7 Air Combat This time I'm going to talk about how Air Combat has changed, and boy, it sure has changed! In

earlier HoI games, air units were all "wings", a grouping of a non-specific amount (but notionally

around 100) planes which you could order to carry out missions in an area or targeting a specific

province. In HoI4 we no longer use only wings; each plane is an individual piece of equipment, and

rather than give each one orders, you give orders to your air bases to send a certain number of

planes on missions to a given Strategic Region.

I'll go into more detail in a moment, but in previous diaries there have been questions about how our

design and development process works, so I thought I'd share a little info about that first. Before

working on HoI4, both Podcat and myself worked on the For The MothlandMotherland and Their

Finest Hour expansions for HoI3, so we already had a lot of ideas about what we wanted to be

different in the next game. One of our main ambitions was reducing the micromanagement needed

for Air units and making the Air game more about your overall campaign goals. You shouldn't have to

manage every sortie. So after seeking inspiration and doing some research, we held a brain-storming

session which resulted in these concrete details being nailed down:




Now, to those of you without years of game development experience, that may look like a jumbled

mess of nonsense scribbles, but rest assured that Podcat, as he says, "doesn't even see the code" at

this point and can make perfect sense of it (perhaps one day I will develop this skill too!). After that

we write up a proper design based on our notes from the meeting and start turning that design into

code and actual bits of a game. For example, here is an early debug screenshot showing a stream of

German fighters and bombers attacking Britain:

We often do visual aids like the above when developing new graphical systems. The red lines show

possible generated attack paths for planes as they attack, while the blue lines show their return

paths. Which attack/return path they take varies so not all missions follow the same path and things

look nice. Of course, we do not show every dogfight in real time on the map. The planes on-screen

represent the average goings-on in an area, so if there are fighter battles going on in a region you will

see a dogfight happening, with whoever is getting the worst of the battle being shot down.

And here is how air combat currently looks, although it is still in development:




We've made various other changes to how planes work in HoI4:

Rather than artificial stacking limits, Air Combat is limited to 1v1 or 2v1 fights within larger battles. Overall numbers still matter, but only so many planes can effectively engage another at one time. We felt this reflected real historical battles much more closely.

No more Interceptors or Multirole Aircraft. Instead, we have Fighters and Heavy Fighters, the latter being twin engine planes which are faster and more heavily armed but less agile. Historically, not many planes perfectly fit a specific role, so it will be up to the player to decide in what direction to steer plane development. In general, Heavy Fighters are good at shooting down Bombers, but have trouble against more agile Fighters. Fighters can shoot down Bombers too, of course, but being less heavily armed they take longer to do so.

Speed now affects targeting order in combat. Faster planes get to pick their targets first. Because of this, speed and firepower will be the most important attributes for planes you intend to intercept bombers.

Agility is a new stat. When two planes meet in combat, the more agile plane will be able to use a greater percentage of its Air Attack value.

Coverage is more a concept than a stat, and is based on a plane's Range stat compared to the distance to the center of the Strategic Region it is operating in. Planes which can just barely reach the target have a poor Coverage value compared to a plane that can fly laps around the area.

While individual planes do not gain experience, combat/missions have the possibility of generating Aces. Aces can be assigned to Air wings and improve the efficiency the planes. We'll talk more about them in a later dev diary.

Now, getting back to how air missions work: HoI4's map is divided into large areas which we call

Strategic Regions. These are the targets for Air Missions. To give you an idea of the size, mainland

France is divided into just two Strategic Regions. You can give orders to any air base within range of

the region to send however many planes you want, set mission priorities, and can then largely leave

the planes alone to fight it out until you want to change orders or just monitor their progress. The

balance of forces in a given Strategic Region affects the Air Superiority value within it, and when Air

Superiority is lopsided it will affect how often the weaker side can carry out missions. This will also, of

course, negatively affect the operation of ground forces in the Region.

Actual missions (and let's assume a Strategic Bombing mission for this example), barring bad weather

or enemy air dominance, are flown twice a day - a daytime and nighttime flight - and will either

follow priorities set by the player or be split up logically if the player has set no priorities. When a

mission flies, it has a chance of being detected by the enemy based on weather, Day/Night, RADAR

coverage, enemy Air Superiority, etc. If it is detected, the enemy's defending planes may intercept it.

Enemy planes will prioritize attacking bombers, but the mission's escorts have a chance to catch

intercepting aircraft. After the air battle is concluded, the mission continues with available aircraft.

The damage done will be affected by not just the number of planes sent, but also a Disruption

Penalty, calculated based on the proportion of bombers sent that were engaged or destroyed while

on the way to their target.

Overall we hope the Air War in HoI4 will be more a matter of Planning and Production than

micromanaging Air Wings. It is intended to be something that will require you to wear down an

enemy's air force with campaigns of attrition before your own air force can really cause major

damage to their country with strategic bombing. As you can guess, many of these changes also affect

how Carriers work, but that's another subject of a future DD.




Dev Diary 8 Experience and Variants This week is going to be a pretty short diary because we are all super busy preparing for Gamescom

and Paradox Fan Gathering in Cologne, but because we are physically addicted to stress hormones at

this point we love our fans we decided to squeeze one in anyway.

A big problem when doing historical games is player hindsight. They will know what works and what

doesn't and tech rush to those points. For Hearts of Iron IV we want players to have to play through

the war to gain the experiences that historically may have been required to make the technological

choices. To accomplish this we have split up the tech system in a theoretical part which is just your

plain old research, which will unlock new equipment, like for example a P-51 Mustang that can then

be produced etc. The other part relies on actual field experience in war and lets you tweak and

modify any of your models to create new models (which you may name as well).

Let's talk about Ship Variants for a moment. Much like with the Division Designer, the key resource

here is XP, although in this case we use Naval XP. Using your NXP you can make changes to any

model of ship you can currently produce. Each ship can be upgraded in four areas, although this is

not the same four areas for each ship type.

In the example here we can see a Carrier, and that it's four possible upgrades are:

Armor - Increases protection, primarily from air attacks, but reduces Speed and Deckspace.

Deckspace - Increases number of Aircraft carried.

Engine - Increases speed.

Reliability - This stat is a little more complicated than the others. The other 3 upgrades all reduce

Reliability a little while this upgrade counters the effect. Could also be thought of as "systematology"

or "ship-shapedness", it's basically how well put together the ship is. A low Reliability makes the ship

more vulnerable to critical hits in combat.

You can choose to upgrade all four areas of the ship, of course, and get an all-round better ship at a

high cost, or you can only upgrade a few stats and have a more specialized ship. Oh, and an

interesting thing about ships is that you can change their variant during production, although this will

impose increased production time depending on how far along in the build process they were when

you changed them, so if you decide your battleship simply must have 18" guns or a better engine you

don't need to build it from scratch - although you cannot make large refits to ships once they are

built.




Dev Diary 9 Vacation and Air Tech Most of the HOI4 team is currently on a much needed summer vacation, but we figured we couldn't

just leave you hanging without a diary this month, so let's get to it *puts down beer* *cracks

knuckles*.

The Air Technology tree is similar to the Armor tech tree we showed back in Diary 2 in that we are

focusing around chassis and unlocking specific historical equipment/models that those versed in

WWII will be familiar with.

Hearts of Iron III had a lot of different airplane classes but that still ended up not being able to match

what nations historically did with their planes, which was use them for many different roles. In HOI4

we have gone the other way and dropped a few classes while instead letting you specialize them in

the direction you want to go yourself using field experience (see Diary 8 for more details). This means

that Interceptors, CAG (Carrier Air Group) and Multi-Role from HOI3 are gone and its up to you to

decide what models to tailor for each role. Do you specialize to create the perfect plane for a role, or

try to develop a fighter that can fulfil all your different fighter/interceptor/escort needs for ease of

production?




Air technology is split up around 3 airframe sizes: Light, Medium and Heavy. Light is single engine

while mediums are generally twin engine and Heavy have 4 engines or more. After the invention of

Jet engines it's also possible to research powerful jet models. Each of the light airframe techs also has

a sub-tech that unlocks a carrier capable model. We felt that extra research investment was

necessary for this because of the trouble many nations had with perfecting their carrier-based

planes. This also highlights another important change from HOI3 - instead of the CAGs you are free to

put any planes that are capable on your carriers and thereby configure their capabilities for different

types of missions. There are also experimental rocket interceptors available, but they live among the

Secret technology tree so we will talk about those later.

That's all for now folks, time to get back to the beer! Next diary is probably going to be about the

naval aspects of the game.

oops, I almost forgot we promised to include a picture of one of Darkrenown's dogs. Here is Domino

testing out the new naval invasion code for HOI4:




Dev Diary 10 Naval Combat It's time to start talking about how the naval aspects of the game are changing with Hearts of Iron IV.

There are a lot of aspects of naval gameplay, so we will be splitting this up in several diaries. Strategic

warfare and details on missions will be in later diaries. This one will focus on direct combat and the

general idea.

We had a few goals when designing naval mechanics for HOI4. We wanted it to both be able to

handle the case of German surface raider ships relying on firepower and speed to tie up a large

portion of the royal navy with a few ships like what happened early on in the war and the massive

naval battles of the pacific between Japan and USA. We also wanted different ship types to be able to

interact with each other and not make, say, convoy raiding a completely separate system.

What makes naval action so different from land is that the position of everything is not precisely

known. So just because you know there is a German ship in a sea zone doesn't mean you can find it

before it leaves. To solve all this ships use both strategic areas (see Diary 7) and exact province

locations. A task force of ships can have missions in a strategic sea area and this can cause events to

happen. A naval event can be fleets coming into contact, or a raider or submarine finding enemy

convoys. Once one of these happen the location is displayed on the map as a combat. Each mission

(we'll talk more about these in a future diary about strategic warfare) controls how the naval task

force is spread out. So for example if you set your task force to patrol an area they will spread out as

much as possible increasing chance of finding an enemy, but because they are spread out only a

smaller part of the fleet will actually make initial contact with the enemy. If you set up your task

force on more of a search & destroy mission they will stick together and be much less likely to find

lone ships, but when they do run into something most ships will be there for the initial confrontation.

Typically this is something you'll want if you are fighting a large enemy fleet. Notice how I said initial

contact, thats because naval battles can be longer affairs of positioning. Lets look at a picture:

http://www.heartsofiron4.com/http://www.heartsofiron4.com/



The area in the middle is the active combat area with the ships distance to the center

showing their relative distance. To each side is an area showing part of the enemy navy on

the way. Depending on your intel you may or may not know what is coming (or just that

*something* is coming) there. As an example from history here take a German fast heavy

cruiser like the Admiral Graf Spee, hunting British shipping early on in the war. The British

will be hunting for it in turn, but are spread out (so they can actually find it) so it will actually

only face a smaller part of the royal navy at a time. Having strong armament and speed

means that it may be spotted by a British cruiser with a larger fleet trying to get to the

location of the battle to give support and the Graf Spee has a chance to take out that cruiser

and get away before the rest arrive, which if it happens means they need to locate it again.

This should hopefully mean that even small technically advanced navies have a place in the

game.

So what about more even combat, like shown in the picture above? When large fleets meet

the game will divides them up in groups of ships that will exchange fire because they may

enter the battle from different directions and at different times depending on spread etc.

Each of these groups is optimally one or more capital ship with a decent ratio of screen ships

like cruisers and destroyers. Screens are very important because they defend the larger ships

from enemy small ships that can carry torpedoes. Torpedoes have lower hit chance but

when they hit they do a ton of damage on large ships. We have tried to make sure each ship

type has a role to play in the battle, so for example destroyers are cheap screens that can

evade large caliber fire, add anti-air capabilities and let you detect and neutralize

submarines. Cruisers are good at at taking out other screens and carry torpedoes making

them dangerous to capital ships if they get close enough. Heavy cruisers, Battlecrusiers and

Battleships can take a lot of hits and carry a lot of firepower and Super Heavy Battleships add

Cool and Flair to your fleet Carriers work like a mobile air field and can carry a variety of

carrier-capable planes to project damage across the battlefield. Finally Submarines are good

at destroying convoys, but can also fill a role in regular fleet combat should the enemy be

low on submarine detection. A submarine starts out hidden and is either spotted if it gets

too close to a destroyer or after firing a torpedo after which it will try to escape. It won't be

an effective weapon against an enemy with a proper fleet, but unescorted capital ships

won't have much defense. Again, another thing in favor of trying to develop a balanced fleet

rather than specializing.




Hearts of Iron IV Development Diaries (Click PIC-Links!) 1-11

Dev Diary 11 Map & Graphic Welcome to the art portion of Hearts of iron 4(HOI4) dev diary series. This diary will focus on the

visual aesthetics of the game and sexy graphic-stuff.

My name is Joakim Larsen and Im a 3D artist working with the HOI4 team on giving players of HOI4

the most visual pleasure out of the game.

Today we are happy to show some of the work we have done on the graphic side of HOI4.

For this dev diary, please ignore borders and country colors. Focus instead on the visual look of the

images we will show. Borders, country colors are not final and are subject for change (Podcat: I know

he says that, but I also know you all can't resists ).

When we first started out working on HOI4 we knew that we wanted a realistic feel for the game

(realistic in a way that its okay having a 5km tall man standing in your province).

We felt that a realistic style would match the game and setting, World war 2 isn't childsplay(right?).

Therefore instead of going for example a more stylized handpainted look we have gone with a

realistic rendered style meant to mimic reality.

For this we have improved our lighting and shading substantially. Instead of just having texture

channel control the specular of the item, we now have both glossiness, reflectivity and metallness

(yes thats an actual word). We also use HDR, all adding up to giving a more physically correct look,

and adding to the feeling of realism.

We also knew that we wanted to do alot better than Hearts of Iron 3(HOI3).

Say what you want, sure it has its charm - but I hope I wont need to have this argument after this

dev diary.



With doing a world map that allows the player to be at a lot of different distances and anywhere in

the whole world comes a lot of challenges.

Main ones are: How do we make the game look and play fantastic everywhere and how do we make

the game look and feel different and interesting in various areas of the world meanwhile staying true

to the real worlds map and making sure gameplay works?

The map has been through a lot of iterations, changes, paintovers and hard work to get to this point

and we are now very happy to show it in more detail.

Gradient borders

In all our games we have tried to make the game look as pretty as possible, this is what is shown in

screenshot and trailers. Unfortunately, this is not how players choose to play, the info you need is

not clear enough in terrain map mode, so political map mode is the only choice.



So in HoI4 we finally had the opportunity to try a solution we have had in mind for a while. Have a

terrain map mode, with large fading gradient borders. Along with having political map mode fade in

as you zoom out.

This way we can have the cake and eat it. You can clearly see countries territories when you zoom

out. And when you zoom in, you can still clearly see the country border, while at the same time

clearly seeing the terrain.

We have built a system that enables us to control the lighting and mood depending on where you are

in the world. Depending on what zoom distance you are at, and what season youre looking at, what

time of day it is and if you are far out on the sea.

In short the desert feels warm, Europe feels green and winter feels cold.

We think this will make the world more believable and varied and that its a really nice visual flavour.



Terrain types

In HOI4 each terrain-type will have different penalties or advantages therefore its vital that it is

crystal clear to the player so that you can see what terrain type a area has.

Weather

Weather has a big impact on gameplay but was in HOI3 hidden away in a separate mapmode which

you quite often did not look at. HOI4 now displays weather directly on the map depending on zoom

distance, to make it instantly clear what is going on. We will have another diary later focused on all

the gameplay aspects of weather, but we simulate rain/storms, snow/blizzard, mud as well as sand

storms currently.



Day and night cycle

Hearts of Iron has always had day and night, and the time of day matters. This has however not been

very clear. Very early on we added night and day cycle and loved it instantly.

This feature has meant trouble for art at every turn, but we still think it adds a lot to the game, both

aesteaticlly and gameplay wise.

During the nights city's light up, and everything get a more night-look.

Fog of war

To show the player what's visible and not we have fog of war(FOW) so its visually clear for the player

what's visible and not.

We have chosen to go with a foggy-cloud FOW that shows mountaintops, hills and trees rather than

darkening like in EU4 so that it isnt confused with night/shade. This looks quite nice and fills its

purpose.


Characters and tanks

With HOI4 we wanted to really make the characters and tanks be as good as possible since they are

key gameplay markers on the map. We start with making a high resolution polygon model of the

character. When that model is as good as its get we start doing a low resolution model. Then we use

various methods of transferring the details from the high resolution model to the low resolution

model, making them indistinguishable with the use of normal maps. That starts off the texturing

process where we give each area texture and makes the model pretty.

Thats all for this time! Hope you like what you see. We are proud of alot of things with the map and

alot cant really be told or shown in screenshots - you have to see it for yourself to really enjoy it.





Dev Diary 12 Internal Politics Hi everyone, we are now back from holidays and hard at work making games, so it's time for another

dev diary. In this one we are going to talk about internal politics as well as give you an update on

project schedule for Hearts of Iron IV.

Political Power

Political power is a new currency in Hearts of Iron IV. It models how much control you as a ruler have

over things. Political power is gained over time automatically, but there are also ways of gaining

more quicker, which brings us to National Goals.

National Goals

A national goal is something you set up as a promise or mission to the nation. Picking one will cost

you political power, but you'll usually get it back plus more reward if you can show that you were

able to accomplish it. It might be a specific historical goal (which is a great way of pointing the AI in

the right direction btw) or something more lose, like a campaign of improving the nations roads.

We modeled this mechanic around how Hitler historically secured his grip on Germany and started

WWII, the idea being that you need to pull off some stuff to build confidence in your ruling powers.

There were groups convinced that he would bring ruin to Germany and were about to stage a coup

vs Hitler as he went from breaking treaties by putting German military presence in the Rhineland and

onwards to annexations of Austria and Czechoslovakia. Hitler gambled right that none of the League

of Nations members felt strong enough to flex their muscles and stop him. I have a feeling there was

a generous serving of good luck there, but nevertheless the effect was that his political power grew -

he had been right when everyone else argued caution. Well at least short term, and this let him

dictate policy without being questioned.



Ministers & Government

Your government is filled by you by spending political power. Some ministers may be hard, or

impossible to get rid of, some may cost an upkeep of political points every week to work for you, and

some may even help your political power grow faster. Ministers can have both positive and negative

effects on the country. For some posts ministers are mutually exclusive, so you can only pick one

from a group. This is true for all military top positions, such as head of army, navy and air force where

we have a couple of different people to pick from, all with their specialties. For example, Germany

can pick between 3 heads of the air force: Hermann Goering - who favors Ground attack missions,

Ritter von Greim - who reduces weather penalties, or Albert Kesselring - who enables faster

experience gain.

I think setting up the perfect cabinet will be a very interesting job in HOI4.

Companies

Tech teams from HOI2 was something a lot of people missed in HOI3, so we wanted to bring them

back somehow in IV.

In HOI4 we call them companies, and, just like other things in this diary require political power to be

selected, or to remove/change. They generally always come with a research bonus to a particular

field and for most categories you can only select one company to be responsible for development of

new models. Lets take tank research as an example, both Porsche and Henschel give you the same

research speed bonuses, but tanks developed when you have picked one of them will have different

starting stats. Porsche tanks will get an edge in armor, but suffer lower reliability and speed vs

Henschel's designs that have better reliability and a small edge in firepower. With this we hope to

add even more cool flavor to companies and make equipment from various countries a bit different,

even if its tech of comparative years.



Laws

A subset of ideas, Laws are basically a group of ideas which are linked. You always have one, and only

one, Law set for each group. You can freely change between Laws as long as you meet the trigger

conductions for the Law you want to use, but the Political Point cost is higher the further away from

your current Law it is. For example, there are 7 Conscription Laws, the first is Disarmed Nation, the

6th is All Adults Serve and the last is Scraping the Barrel - It costs a lot more PP to move from

Disarmed Nation to Scraping the Barrel than it would to move from All Adults Serve to Scraping the

Barrel. Extreme Laws are not always entirely better, Scraping the Barrel does grant the most

Manpower, but it fairly significantly lowers your industrial output and the maximum Training Level of

your divisions.

Elections & Public support

The nations in Hearts of Iron which hold democratic elections will find themselves in some special

situations. If the public is concerned that the administration doesn't handle the current situation

adequately, they may voice their dissent, making the rulers choose between facing lower public

support and a nation that stands less unified against outside threats or making changes to policies or

the administration to appease the voters. Although exceptions can be made in times of war, an

administration that handles conflict poorly may see itself replaced.



Additionally, democracies are not immune to the effects of communist and fascist movements that

defined much of the politics of the era. If the popularity of either grows strong enough, the ruling

democratic party may find it necessary to form coalition governments with these parties. Such

arrangements come with their own strengths and weaknesses, as these partners may use

international ties among the communist or fascist empires abroad to open up new opportunities and

risks for the nation.

If the public support for the democratic parties themselves wanes, the elections can effectively

abolish themselves in favor of a military junta or vanguard party. Although the old government may

choose to contest this, sparking a civil war, public support for the institution of democracy itself will

ultimately be necessary to maintain it.

However, public support is not the only way another ideology can take over. Shifting the political

allegiance of the nation can also be a national goal, with communists seeking broad support for a

violent revolution and fascists looking for ways to topple the government via military coup. Even a

dictatorship where no elections are held can work to increasing liberties and holding referendums to

eventually move towards democracy. These tumultuous changes can temporarily weaken the nation,

but allows for radical changes to foreign policy.

Release Schedule

On to other important matters. As some of you on the forum have already guessed, we have decided

to move the original Q1 2015 release target to late Q2 2015. Hearts of Iron IV is a very ambitious

undertaking and we might have been a tad optimistic with the original date that was communicated.

Hearts of Iron IV is our most complex game with massive scale as well as a lot of systems and details

you need to get right. It covers a modern period which puts a lot more requirement into the

simulation accuracy and with our new focus of making sure all games we make are solid, playable,

and a lot easier to get into with polished interfaces... well, its a lot of work to make it as good as we

want it to be.

With the new schedule, I'm happy and confident with where we are now with the game and with it

being one of our core titles there is not really any risk of any other delays. After the last spurt of work

we did before Christmas for example we have really seen all the pieces fall into place.

I really hope that you, just like us devs, prefer the idea of the game to be the best it can be on

release. We care just as much of this game as you do.


Dev Diary 1 - Our VisionDev Diary 2 - The Tools of WarDev Diary 3 - Bringing WWII to the mainstream (april fools)Dev Diary 4 - Land DoctrinesDev Diary 5 - Production LinesDev Diary 6 - Division DesignDev Diary 7 - Air CombatDev Diary 8 - Experience and VariantsDev Diary 9 - Vacation and Air TechDev Diary 10 - Naval CombatDev Diary 11 - Map & GraphicDev Diary 12 - Internal Politics

Hearts of Iron 4 Dev Diaries

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Transcript of Hearts of Iron 4 Dev Diaries