Hearts of Iron IV Beginner’s Guide

Hearts of Iron IV is a historical military simulator developed by Paradox. For any gamers out there, who are familiar Paradox, will most definitely appreciate that strategy games produced by them, like Crusader Kings II, are quite challenging when trying to grasp the basic concepts, so in this guide I hope to teach you the foundations of knowledge needed to play this fantastic historically accurate simulator.

Hearts of Iron IV Beginner's Guide

Please note, some of the information in this guide may be outdated after the release of the 'Waking the Tiger' DLC on March 8th 2018. It will be updated soon. In the mean time, please be sure to check out our review of the Waking the Tiger DLC.

Starting the Game

Firstly, welcome to the Keengamer Hearts of Iron IV guide – please be warned this game is not for the weak minded and takes a degree perseverance to learn the ropes. Hearts of Iron IV is a historically accurate World War 2 simulator where you can play almost any nation that existed from the time. Personally, being a bit of a history buff, I think this game is great, but it can be challenging to learn the basic principles of the game, which help you to maximise the enjoyment you will obtain from the game.

Therefore, in this guide the very basic aspects of the game will be covered. In addition, I will go into depth about the interface itself including your laws and government, diplomacy, trade and different scenarios you can play. So, once you have loaded onto the main screen you will presented a choice, do you give it a go by yourself in single player or with a friend on multiplayer? It is of course up to you, but I would strongly recommend using single player to learn the game and its mechanics.

When coming to pick your nation, you will presented with a list of seven major powers in the game (France, Great Britain, United States, German Reich, Japan, and the Soviet Union) for your first game I would recommend playing as the German Reich, as they have no overseas territory to manage, and can be very fun to play as, despite me despising the bovine ideals of Nazism. Moreover, they have a decent starting army, high national unity and an overall fun national focus tree. In addition, smaller nations like Hungary and Romania can be fun to play as, due to them being small and having an interesting national focus tree (yes, we will get to that later on). 

On the main menu there is also an 'options' section which allows you to adjust your game and music volume accordingly as well as the user preference on graphics.  

The 'Got to' knows

Choosing a scenario

Hearts of Iron IV offers two scenarios for the player, either one where you start in 1936 or 1939, whichever one you decide to pick, it will ultimately determine what type of start you will get.

The world in 1936

The 1936 scenario begins on January 1, 1936. The 1936 scenario is the one most likely to lead to alternate versions of World War II, since it starts with fewer alliances or wars to start. 1936 is the place to begin in order to play through the organization and planning of an economy before the war starts. This scenario is about laying the groundwork for the armed forces and war plans, opening with a focus on production, research and diplomacy.

The world in 1939

The 1939 scenario begins on August 14, 1939. The German Reich has consolidated its power in central Europe and is primed to attack Poland. For a game about World War II that will be more likely (but not certain) to evolve as the real war did, it is advised to start here. This scenario is more about building, supplying and leading land, sea and air forces.

The Interface 

Now we begin to dive deeper into the actual game itself. You have picked your scenario, as well as your nation, and will now you have loaded into your game. This can be very overwhelming, thus why I am here to help you. So, please take a look at the top of your screen, as this is the part I will be discussing.

National Unity 

To the right of your selected nations flag, you will see something that resembles three squares in the shape of a triangle. This is your nations national unity, which is a measure of war-resolve in your country. While fighting a war, the lower the national unity, the less time it takes for a nation to capitulate (take) your country. For example, France starts with a very low national unity, and does not take as long as Germany to capitulate, who have a 90% national unity. Also, a low national unity can lead to rebellions in certain states. National Unity can often be improved/modified in certain national focuses.

Politcal Power

Next to your national unity is your political power, something that resembles a government styled building. This is the amount of political capital your nation has, and can be spent on national focus ideas and the appointing of ministers, generals, theorists and different companies to your government

HOI4 Beginner's Guide - The interface itself

Continuing right, we see manpower, which shows you how many people are available to be trained for the military in your nation. Different conscription policies (brought by political power) can increase or lower this amount.

Army, Naval and Air Experience

As units fights they can gain experience. Army experience can be spent in the unit designer, allowing you to upgrade your army. Naval and air experience is used for modifications to ship and plane designs, giving them bonuses in speed, firepower, reliability etc.

World Tension 

Now we move away from the left side of the interface onto the ride side looking at the globe. The indicates the world tension. Some nations who are neutral or have democratic system in place need higher world tension to begin war justifications on facist and communist nations such as the German Reich and People's Republic of China. World tension is increased by certain events, war justifications and other hostile diplomatic actions.

HOI4 Beginner's Guide - Some events can increase or decrease the world tension

National Information

Slowly but surely we a progressing through this guide. Currently, we have covered the basic aspects of the game from choosing your nation and picking your setting, to the very basic elements of the game including political power and world tension.

Over the top left of your screen, you will see the picture of your nations flag – click it. This will open up your national settings, and show what party is in charge including the other opposition, as well as your leader portrait and national spirits e.g. Military Youth. As well as this you can manage your occupied territories (if your nation has them) by clicking the occupied territories button, this allows you to release states you own or you have captured in war.

Arguably the most important is part of your national information is the national focus tree. Players will be prompted when the there is no national focus active. It normally takes seventy days to complete, and costs some political power to complete. They allow the player to move towards different polices so for example you may want to focus on buliding up your nations infrastructure, which allows your infantry to move faster.

Laws and Government 

  1. Conscription laws: affects the amount of manpower in your nation
  2. Trade laws: affects research speed, factory and construction speed, and the amount your nations resources that be exported 
  3. Economy Law: affects how many of your nations factories are dedicated to domestic goods and how many are dedicated to military construction  
Research and Production 

A tank designer, ship designer, aircraft designer and material designer can be added to increase the construction or research speed of the relevant weapon system, affecting combat capabilities.

Military Staff

A Chief of Army, Navy and Air Force can be added to improve combat skills in their specific area. Three other High Commanders can be appointed.

Science and Research 

The grey button located next to your nations flag, with the scientific looking flasks, is your research section. Dependent on your nation, you can start from two to four research slots. Furthermore, you can research certain items in eleven different categories including:

HOI4 Beginner's Guide - A research tree example

Researching better infantry weapons and different types of infantry divisions. This is where to go to unlock mechanized infantry, paratroopers, marines, mountain troops and so on.


Researching support companies that can be attached to divisions. These include engineers, medics, mechanics, and so on.


Research light, medium and heavy tanks, as well as variant tanks based on the chassis unlocked.


Researching artillery, anti-tank and anti-aircraft weapons.

Land doctrine

Most of the great powers will start with an initial land doctrine. This may be changed, but all land doctrine paths are mutually exclusive. Each land doctrine chosen assigns its own major combat bonuses.


Researching more advanced warships, submarines and convoy/landing craft.

Naval doctrine

Some of the great powers will start with an initial naval doctrine. This may be changed, but all naval doctrine paths are mutually exclusive. The chosen naval doctrine will assign major combatbonuses.

HOI4 Beginner's Guide - Eventually you can research powerful nuclear weapons

Researching different types of fighters, attack planes and bombers as well as carrier borne variants.

Air doctrine

Some of the great powers will start with an initial air doctrine. This may be changed, but all air doctrine paths are mutually exclusive. The air doctrine chosen will assign major combat bonuses.


Researching electrical engineering for radars (for detection) and computers (for research and encryption bonuses), as well as researching nuclear and rocket technology


Researching means to improve the efficiency, productivity and resource extraction capabilities of the player's country.


This section is relatively simple. It is located next to the research section, and looks like a shaking hand. Once clicked, this shows the relations your picked nations has with other nations. This is especially useful when playing a democratic nation, as you can see how close you to being able to justify a war goal against them.


There are six major resources in the game: oil, rubber, aluminum, steel, chromium and tungsten. These are used to help in the construction of tanks, battleships, planes and so forth. Each new production line of a major weapon system will require a certain amount of resources. Though one can build these units without the necessary resources, production will be much slower and less efficient.

Resources are found in certain locations on the map and are not evenly distributed. One will almost always have to trade for what one needs.
To trade for a resource, click on the name of the country and move the slider to determine how much one is trading for.

HOI4 Beginner's Guide - Some artwork for the Kaiserreich mod

Resources are traded in units of 8. Each trade, unless conducted over land, requires a minimum of 2 convoy vessels plus 1 for every additional 4 units of resource. Every 8 units of a resource one imports will also cost a civilian factory, with that productive power going to the nation that is traded with. So, exports will make one's industry stronger as one pulls factory power from other nations, but a lot of imports will make one weaker, but a country will need to import resources to keep its war machine going.


Civilian factories make all the improvements to a State. The number of factories available for construction will depend on the size of the nation, how many factories are being dedicated to providing consumer goods for the country's population (Economy Law), and how many factories have been “traded” for strategic resources. The amount of civilian factories can be increased by building more, but be careful since each State can only support a certain number of productive structures. A maximum of fifteen factories will be devoted to a construction project, and any left over will work on the next item in the queue. The types of buildings you can construct follow:

  1. Infrastructure: Each state has an infrastructure rating that determines how easy it is to supply units in the state and how quickly military units can move through.
  2. Air base: The larger the air base, the more planes it can effectively field. Air bases house military aircraft.
  3. Anti-air: Defends a State from enemy aircraft, and especially useful to protect industrial areas.
  4. Radar station: Help the airforce detect and intercept enemy air fleets.
  5. Military factory: Used to produce weapons, equipment and vehicles
  6. Civilian factory: Used to produce and improve a nation's military/industrial capacity
  7. Synthetic refinery: Produce synthetic oil and rubber, especially useful to nations that lack either
  8. Naval dockyard: Used to produce ships and convoys. Can only be built in coastal states.
  9. Rocket site: Locations from which to launch rocket attacks on nearby nations
  10. Nuclear reactor: Produces nuclear weapons
  11. Naval base: Assists in overseas supply limits and ship repair speed
  12. Land fort: Hardens the defense of units
  13. Coastal fort: Hardens the defense against amphibious attacks


The more factories one dedicates to building a specific item, the more of it one will produce. Army equipment and planes produced will then be assigned to the appropriate military divisions and air wings, either for new units one is constructing or reinforcement and upgrades for units in the field. Excess equipment is left in the national stockpile. Naval units will be automatically placed in a port, though one can assign a port or fleet if that would be preferable (recommended for the Soviet Union so they don't end up with all new ships stuck in the Black Sea).
Factory output is dependent on the availability of strategic resources for higher end units, and on the efficiency cap of a country's industry. New production lines will take time to be perfectly efficient, and if one adds factories to a production line, some of that efficiency will be lost. The factory productivity and efficiency can be improved in the Industrial research tree.

RECruit and deploy 

You start with a few default divisions you can build. You can spend army experience to design a new division template or edit ones that already exist.

HOI4 Beginner's Guide - You can edit your army divisions using army experience gained from theorists and battles

The game starts with reinforcement and upgrades given equal weight with the creation of new units. If you would rather focus production of new tanks or artillery on fresh units, instead of trickling equipment to the field, it is possible to set reinforcement priorities on this menu as well.


This menu gives an overall summary of your stockpiled equipment, whatever shortages one might have, as well as a rundown of how many strategic resources are missing for one's production lines.


Overall, the basic foundations of this game have been covered. Unfortunately, I thought it would be a wise decision 'not' to cover the military side to the game, and cover that in another guide. Once the basic elements of the game are explored (which hopefully I have helped with) it will help you to understand how the game works, allowing you to explore deeper into its mechanics. 

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