The Ultimate Hearts of Iron 4 Guide

Author: James Broomfield

Hearts of Iron, Past and Present

Hearts of Iron 4 (commonly abbreviated to HOI4) is the latest in a series of popular World War 2-themed grand strategy games released by Paradox Interactive, a longtime strategy game developer. As the studio has emerged from its initial niche, independent market with successful mainstream titles such as Crusader Kings 2, Stellaris and Cities: Skylines, Paradox has redoubled its efforts to bring Hearts of Iron to a huge audience with this latest release. The older iterations of the game have always focused on resource control and management of armies, navies and air forces. Hearts of Iron 4 retains the basic infrastructure of the previous titles, but the game is fundamentally different in some key ways that both make it more accessible, and add significant depth.

Art & Music

One thing that players will notice right away is the improved, modernized graphical interface. To put it simply, the game is much easier on the eyes than prior titles. Some of that has to do with age, as Heart of Iron 3 was originally released all the way back in 2009. But even when they were brand new, the older HOI titles had a well deserved reputation for overwhelming players with a complicated and graphically unimpressive display. Dark and dingy colors, blocks of small text and jagged edges predominated. This served as perhaps the biggest barrier to entry for new players, and Paradox clearly took note.

In Hearts of Iron 4, the map is a pleasure to look at. The drab and dreary maps of old are replaced with bright colors, crisp lines and bold text that render the geopolitical situation in 1936 in perfect clarity. Minor quality of life improvements abound, as players have access to a 24-hour day and night cycle. City lights illuminate the night sky in major urban areas, and air wings engaged in missions can be seen flying on the minimap. Terrain is overhauled and re-textured, with snowy mountain peaks contrasted by deserts engulfed in sandstorms. The improvements don’t stop there, as national political and military leaders also receive portrait-style artwork based upon some of their most iconic photographs. Much of the artwork in this game is truly beautiful, and captures the time period in a much more serious and immersive way than prior titles have managed.

The game’s sound design, music and soundtrack are also fantastic. Paradox has been working hard to make the soundtracks for their new titles, and Andreas Waldetoft has done an excellent job. Sweeping and epic scores populate the game, and each track has a thematic prompt that truly evokes the feeling of different events and time periods of the second world war.

Improved Systems: Division Designer & Technology Tree

The game also expands upon some of the successful systems from Hearts of Iron 3, such as a rudimentary division template designer and the ability to progress through a technology tree. Previously, players noted that both of these systems were extremely arcane and hard to learn. Many elements of Hearts of Iron 3’s tech tree required extensive online research to understand their effects. All in all, not a very accessible experience for new players. That’s why Paradox decided to completely revamp the game’s user interface, commissioning new art and graphic design and dispensing with the old models entirely. The division template designer was revamped and made more purposeful, with meaningful bonuses and hard counters to opposing strategies made plentiful. The technology tree has been markedly improved, with a clear and concise descriptor for the buffs and debuffs offered by each individual technological advancement, and a clear line of progression to guide the player. Although the division template designer has a slightly larger learning curve, both of these systems have been transformed from a liability in previous titles to a major asset in this one.

Paradox also removed some of the clunkier, more ambitious and less than successful experiments with AI from their latest venture. In Hearts of Iron 3, the player could automate almost every system and hand over total control to the PC. However, HOI 3’s artificial intelligence system was simply not robust enough to handle so many independent and overlapping systems. Oftentimes, the AI would struggle to successfully manage even the computer-controlled nations, and bugs would often appear in the late-game or when using systems such as puppeting. Of course, as any grand strategy gamer knows, these are the predictable aches and pains of a small studio putting out a big project. As they’ve grown, Paradox has improved the trouble-shooting and bug fixing capacity of their team. In Hearts of Iron 4, the player can expect essentially seamless interaction between gameplay systems such as National Focuses and the technology tree. Less can be automated, but the systems that can be handed over to the AI are much more successful in their implementation.

New Features: Industry, National Focus & Battle Planner

Apart from improving and honing the features from their older titles, Paradox added several new features to Hearts of Iron 4 that give the game a truly unique flavor in the series. The most popular overhaul is related to industrial production; in older titles, both civilian and military production was controlled by a single currency, and the player produced divisions in full without regard for their equipment. In HOI 4, civilian and military production are separated, allowing for a consumer economy to shift to a military economy as war becomes more likely, and more accurately reflecting the historical context. The player also establishes production lines for equipment needed by the military; when items are produced for a long time and with the raw materials required in good supply, production efficiency increases and more equipment is made. Instead of arbitrarily producing divisions, the player now must ensure that the equipment needed by the division template they wish to train is in stockpile.

Additionally, Paradox added several elements to make the game feel more like a sandbox-style experience, should the player so choose. Gone are the predetermined political paths and rock-solid permanent alliances of Hearts of Iron 3; in their place, Paradox has introduced the National Focus system. This offers players a tree, not unlike the technology system, but that instead focuses on political pathways and improvements. Every nation has a default, or historical, pathway through their focus tree, which will take them down the political route that mostly closely resembles their real-life performance during the second world war. In addition, however, Paradox has included alternate history paths that allow the player to create an entirely new historical scenario. Democracies can convert to Communist and Fascist dictatorships, and vice versa, all with relative ease. Nations can also influence one another using political power, a currency generated by the type and strength of their government. In this way, the geopolitical map can be completely reshaped, all without war and in just a few years. The player isn’t the only one who can wreak havoc on history; Paradox included the option to turn off historical focuses for ALL countries! Roosevelt can be overthrown in America, and Stalin’s iron grip on power in the Soviet Union broken, opening up endless possibilities. Be warned, the world can quickly go haywire with this setting turned off.

Perhaps the most notable and impactful addition to Hearts of Iron 4 is the Battle Planner, a feature that has been long-awaited by many in the Paradox fanbase. As with any major overhaul, it is controversial as well, but it objectively improves upon some of the more unfortunate shortcomings of Hearts of Iron 3. The third game in the series is beloved by many and offers an extremely rewarding playthrough for the dedicated player, but it is widely considered to be micro-intensive, or too reliant on the micro-management of hundreds of individual units and systems. Each individual division within an army required specific orders to move, making for an overwhelming experience that served as a serious obstacle to playthrough and, importantly, sales. The Battle Planner seeks to solve these issues by automating some of the more basic functions of an army, such as creating a front line, launching a general offensive and garrisoning occupied territory. While they are imperfect, these automated systems are vastly more functional than those in HOI 3, and they generally work well without human intervention. Paradox incentivizes the use of these features by offering a planning bonus, whereby the player will receive a buff to their units when an assigned order is set up and prepared. As noted, this system can be controversial with hardcore, longtime Hearts of Iron players, who find it to be too simple. Overall, though, the Battle Planner is highly successful and one of the most important elements in introducing this studio and genre to a new generation of gamers.

A Basic Strategy for Success

With all of these changes incorporated, what makes for a successful Hearts of Iron 4 playthrough? In many ways, what works for one nation will work for all, and some fundamental steps must be taken in every game. As was true historically, the goal of many nations in the year 1936 is to complete the recovery from the Great Depression, which had wracked the world economy and was still felt acutely throughout the globe. Therefore, the player should focus on the civilian economy in the early game, building civilian factories and infrastructure, and researching technologies that will boost research and economic efficiency, such as computing, construction and industry. A strong civilian economy is capable of readying for war and creating a strong military economy. The player must choose one of two paths with regard to industry; concentrated and dispersed. Concentrated industry allows the player to build many factories within single states, but can leave the player vulnerable if they fail to protect that state or are at a disadvantage in the air. Dispersed industry incentivizes the player to spread their factories throughout the nation and protects them from a decisive industrial defeat, at the cost of efficiency. The path that the player chooses will depend entirely upon the nation they choose and strategy they employ. Beyond this binary choice, the rest of the industrial technology tree depends mostly on speed and the efficiency of a player’s research.

As nations begin to flex their muscles, so to speak, and undertake aggressive or controversial actions such as territorial demands, conflicts and alliance-building, world tension will increase. This metric determines the global climate, and the capabilities of different types of governments. When world tension is low, democracies are unable to intervene meaningfully in foreign affairs, while communist and, more importantly, fascist regimes are given a free hand to do as they please. With each controversial action, however, world tension will increase, bringing the democratic order ever closer to war. As world tension climbs, the player ought to begin to use their civilian industry to churn out military factories, and ramp up production of military equipment. Transition your research priorities away from civilian technologies as well, and begin to research military technologies. It is generally advisable to choose one type of equipment in which to specialize, based upon your nation’s unique profile. Whether you focus on plane, tank or special forces production, it is wise to have a major advantage over the AI, which will generally try to improve all aspects of its military on a gradual basis.

Rising World Tension inevitably leads to global war, so it is time for the player to put the finishing touches on their domestic situation and thereafter look outward. Two other percentile measurements will show the player just how ready they are for war: stability and war support. Stability represents the political situation at home, and is affected by the amount of support among the populace for the ruling party. As the name suggests, war support indicates how ready and willing the people are to take the nation to war, and is primarily affected by World Tension. The player’s goal should be to increase both of these percentages to their maximum possible level; stability is negatively affected by warfare and so should receive particular attention. High stability can also increase your political power generation, which in turn can allow you to further increase stability and war support, and so it is an extremely important measure and should be a main focus as you prepare your nation for battle.

As your nation turns toward conflict and the second world war draws closer, one should begin to draw battle plans and acquire planning bonuses. The primary objective in executing these plans is to secure encirclements, an important element of combat in HOI 4. When an army or army group is cut off from access to their capital both by land and by sea, they are out of supply, and suffer from enormous debuffs and constantly decreasing organization. Just as in historical encirclements like that at Stalingrad, a surrounded army will quickly fall apart and is not capable of effectively fighting. By cutting off their supply, even the most formidable enemies can be rendered weak. As you prepare for war, focus on achieving these types of breakthroughs and encirclements, and design your plans accordingly.

Lifeblood of the Nation: Manpower & Resources

The key currency in warfare, and therefore the key currency to overall victory, is manpower. This statistic quantifies the number of able-bodied men within your nation who can be pressed into military service. As the game progresses, nations will have only a few opportunities to increase their manpower, and once a soldier is killed he is removed from the pool permanently. It is very important to ration and control your manpower levels, because once you grind the enemy down and they cannot fill their units, victory is assured. Destroy enemy manpower by winning battles, and by encircling and destroying enemy divisions. When the enemy is encircled, they are unable to escape, and any men caught within the cut-off pocket will be killed and some of their equipment seized. That is why encirclements are an important secondary objective of any offensive; not only are the divisions and equipment destroyed and seized, but the enemy’s manpower pool is depleted. Smaller nations with limited manpower therefore pose quite a challenge, and require the player to be extremely conservative with their decision making. One mistake can end the game quickly, and the AI is also keen to encircle, so even automated battle plans must be monitored to avoid a manpower disaster.

Encirclements are not the only deadly supply affliction to watch out for and avoid. As the game progresses, the AI will focus on producing as many units as it possibly can in an effort to overwhelm its enemies. Under certain circumstances, your allies can also overwhelm you with this strategy. As in almost every paradox strategy title, each state or province has an associated supply limit that cannot be exceeded without consequences. In short, single areas of the map cannot support, feed and supply unlimited numbers of divisions and troops. Your AI allies are not cognizant of this reality, and will flood the regions around any theaters of war with troops, sucking out all of the supply and causing the same aforementioned loss of organization and fighting prowess. If a game proceeds for too long, this result is almost inevitable and can result in an intractable global stalemate of attrition. Try to win decisively, and we hope Paradox puts out a fix sometime soon.

Another important element of successful warfare is resource mastery; as in previous titles, Hearts of Iron 4 requires the player to accumulate various resources to aid in equipment production. As technology improves and equipment becomes more effective and valuable, it will require more resources to efficiently produce. If a player controls resources within their territories, a portion of these can be used for free to augment your production efficiency. If, however, the player requires a resource over which they have no control, they will be forced to trade with nations that do have access. These trades can be expensive, because for every 8 units of each resource that the player buys, they will be forced to spend one civilian factory. Furthermore, as the game progresses and war unfolds, other nations will be less and less willing or able to trade their resources, as their inventories are either closed off from enemies or bought out on the international market. Predict your needs early based upon the strategy you’ll employ and the equipment needs you’ll have, and ensure that you have a steady supply of the required resources. In the endgame, resource deficiencies can severely hamper equipment production, and may end up in just as fatal a result as a loss of manpower.

Winning the War: Army Composition & Victory Points

Army composition will be based upon these very same resources; beyond an essential core of infantry, there are a variety of options to research, and each one will utilize different resource inputs during production. Nations replete with tungsten and in need of breakthroughs along a massive front line might invest in tanks, for instance, while nations with access to aluminum and invested in aerial research might build advanced fighter planes. Ground units must take into account the terrain on which they will be fighting; motorized and cavalry divisions are not well suited to mountains but excel on flat plains. The division designer template allows the player to construct a variety of differently specialized divisions, and the currency used to do so is called experience; it can be accrued by the Army, the Navy and the Air Force separately, and is gained from engagements in active battle. In short, as your armed forces fight more and more, you will have the ability to specialize units in order to efficiently do battle across different theaters and against different opponents.

Enemy nations are finally eliminated when their cities, factories and other provinces with Victory Points are captured. When a province is taken, the population, resources and factories within that province are also captured and/or damaged. This environment encourages quick, decisive and targeted offensives that seek to deprive the enemy of their population and industrial bases. Not only do they lose out on those assets, but the aggressor also receives a proportion to use for himself. The amount of manpower, resources and factories available to an occupier depend upon the compliance of an occupied territory; as long as you have surplus manpower and equipment to garrison and control these occupied territories, compliance will naturally increase over time, unlocking more efficient use of the province. Of course, the most important element is denying access to the enemy, who could see their entire economy upended if a particularly resource-rich or industrialized province is taken from them. One decisive victory of this nature can change the trajectory of the entire war!

Now you have the basic outlines for a successful campaign. Many nations have their own unique traits and characteristics that will lend well to specific styles of play, but by following the template laid out above, you’re almost guaranteed a successful and engaging playthrough. Follow this space for future articles with in-depth breakdowns of individual factions and their unique focus trees, leaders and traits.

In Conclusion: Our Review & Game Rank

So what’s our verdict? Overall, we think that Hearts of Iron 4 stacks up very well against its predecessors, despite some reservations amongst longtime Paradox fans that it has been oversimplified. Granted, there are many areas of the game that can feel incomplete, and bugs are not infrequent even years after release. Paradox has long embraced the business model of supporting an initial release with many years of paid DLC; some titles have received major expansions almost ten years after their release! Already, Paradox has rolled out expansions such as Together for Victory, Death or Dishonor and Man the Guns, each pack adding different features to various nations and improving upon core mechanics. Needless to say, this framework can make launch day a bit underwhelming, and as with every Paradox Interactive production, Hearts of Iron 4 is a different, more complex and more immersive experience with DLC purchased and installed. With each DLC pricing at $10-$20, it can be very expensive to attain the full experience. Paradox should reconsider this model and adopt something more conventional if it truly wants to expand its fanbase.

However, in terms of ambition and improvement, the scale of Hearts of Iron 4 simply cannot be denied. This is a game, and a studio, without any serious competitors in their marketplace. Nonetheless, the massive and dynamic overhauls as compared to HOI 3 and older titles, are a testament to the quality of Paradox. The fact that they continue to innovate in major ways is laudable, and as always, the research underpinning this title is flawless and filled with depth and flavor. When coupled with incredible visuals and portraits, a stunning soundtrack and the knowledge that Paradox will continue to refine this game for years, we conclude that Hearts of Iron 4 is a must-have for any PC gamer.

Our Game Rank: 8/10