hoi4 is a game that is easy for experienced people and quite difficult for others, the most important factor underlying this is that the game is complex for the players.

because both the detailed gameplay and the mods that can be downloaded from the steam workshop, as well as the existing and constantly new dlc and updates both keep the game up to date and enthrone the hearts of the players.

Since the game is very detailed, certain elements form the basis of the game.
One aspect of the gameplay that many beginners tend to overlook and pros never ignore is coastal defenses. The attention this task entails obviously depends on which country the player is controlling. Landlocked nations need not worry about this problem.

Any country occupying a coast needs to implement some form of defense sooner rather than later. Unguarded shores easily invite enemy naval invasions. Build plenty of coastal forts and garrison the perimeter with second-line troops. Don't feel the need to construct a colossal chain of defenses. Even modest preparations can defeat enemy amphibious assaults.

When playing as a major nation, it's vital not to neglect the navy. After all, why throw away a helpful resource? The key to any proper naval buildup is variety. New players learning the ropes may be tempted to just focus on one type of ship. However, that strategy isn't always very efficient.

A proper task force meant to engage the enemy should contain a healthy variety of ship types. Veteran players all have their preferences, but a good composition to aim for is around 4:1. In other words, there should be 4 screening ships for every 1 capital ship. Here's the breakdown of what constitutes screen and capital ships:

Screen Ships
Light Cruisers
Destroyers
Capital Ships
Aircraft Carriers
Super Heavy Battleships
Battleships
Battlecruisers
Heavy Cruisers
The reason for this variety is that each ship type has its own strengths and weaknesses. A task group only composed of one ship type can be outmaneuvered/outgunned by a superior enemy navy. A variable collection of ships, on the other hand, is ready for anything. In addition, submarines can be grouped separately to form "wolfpacks" to terrorize enemy convoys.

In the race to churn out as much infantry and guns as possible, it's easy to forget about Special Forces units. Special Forces come in three varieties: paratroopers, marines, and mountain troops. To maximize the efficiency of these troops, it's best to look at the map and plan ahead. Play to each unit's strength and watch them go to work.

Let's use a naval invasion of Great Britain as an example. A German player will want both air and naval superiority over the English channel (use that variable navy!). Marine battalions may want to secure the ports in preparation for the arrival of the main army. Paratroopers can also be dropped behind enemy lines to cut supply routes and hold major cities.

In this example, mountain infantry will not be very useful overall due to England's terrain. It's important to remember that players are limited to the amount of Special Forces units they can train. A cap limit is instituted, whereby Special Forces can't exceed more than 5% of the player's total battalion strength. As such, don't waste resources on training units you won't need!

Occupation is now a more complicated endeavor in Hearts of Iron IV than it was at the time of release. Players hoping to directly occupy every single territory they conquer are going to have to invest extra time and resources to make sure it's secure.
A territory that's successfully occupied will yield more resources and factories for the player. However, clamping down on resistance effectively is essential. Otherwise, habitual sabotage by the angry populace won't do the player much good. A worthwhile alternative involves setting up collaborationist governments. Although players won't directly administer the territory, the headaches of collaboration will be passed on to a semi-independent puppet government.

Research is vitally important in keeping pace with other nations in Hearts of Iron IV. Among other things, research makes industry more efficient and combat units more deadly. The faster a country can conduct its research the more of an edge it will have over its enemies.
Large, more developed countries tend to start with three or four slots already unlocked. Small and less developed nations only start with two, thus suffering from a disadvantage. Regardless of the initial count, smart players should always prioritize National Focuses that grant an additional slot. Outproducing and outgunning one's opponents ultimately result in victory and research serves as the linchpin.

Now, what to do with all those research slots? Technology that benefits the military should never be neglected, but neither should production. Efficient production is imperative for keeping those tanks and planes rolling off the assembly line in short order. Research plays a key role in maintaining that efficiency.

At least one research slot should always be kept open for an industry technology. Playing as an Axis country, it's typically a good idea to choose the Dispersed Industry tree considering the threat of being bombed is quite high. Allied countries, like the United States, can get away with Concentrated Industry. In addition, always prioritize Production, Construction, and Fuel/Rubber technologies whenever possible to stay ahead of the curve.

and last one ...

20th-century warfare cannot be conducted without fuel. Nearly every unit in the game requires some degree of fuel, whether it be tanks, half-tracks, artillery, ships, or planes. If a nation's entire fuel reserves are depleted, units will still move but will start to suffer massive combat and speed penalties.As such, players always need to keep an eye on their fuel levels. Building synthetic refineries help, but fuel silos also need attention. Larger fuel silos mean larger amounts of oil that can be stockpiled for future use. Invading and occupying countries with large amounts of oil is also a helpful strategy. Don't let those tanks run dry!

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