Hearts of Iron IV

Most games about the Second World War hand you a rifle. Hearts of Iron IV hands you a treasury, a research budget, a factory allocation screen, and a map with thousands of provinces on it, then asks what you intend to do about Poland.

Developed by Paradox Development Studio and published by Paradox Interactive, HOI4 is the fourth entry in a lineage stretching back to 2002, and the studio’s most successful attempt at making grand strategy legible to people who don’t already own a copy of Wages of Destruction. It launched on Steam on June 6, 2016, and has been in continuous development ever since — a decade of free patches and paid expansions that have rebuilt supply, rewritten the Soviet Union, added tank and plane designers, and turned what was once a fairly rigid historical wargame into something closer to a twentieth-century political sandbox.

The market positioning is unusual. This isn’t competing with Call of Duty or even with Total War. Its real rivals are Paradox’s own catalog — Europa Universalis IV, Crusader Kings III, Victoria 3 — and the comparison flatters it. HOI4 is the studio’s most-played title on Steam by a wide margin, with a strongly positive reception that has held up across a very large body of player reviews. That’s remarkable durability for a game whose core loop involves staring at a paused map for forty minutes deciding whether to build more military factories.

You can play as any nation on the 1936 or 1939 start. The United States. Germany. Also Luxembourg, if you’d like to see how a nation with a two-division army handles the Wehrmacht. That universality is the pitch, and it’s not marketing fluff — Paradox actually built the systems to support it, and the community has spent ten years finding the absurd corners of that promise. It’s less a game about WWII than a machine for generating alternate 1940s, and understanding that distinction is the difference between bouncing off it in two hours and losing four hundred.

• Nation-Specific Focus Trees: The narrative engine. Each major (and increasingly, each minor) power gets a branching tree of national decisions that unlock territory claims, political shifts, wargoals, and civil wars. Restore the Kaiser. Keep America isolationist through 1945. Have the Allies pivot and declare on the Soviets. These are the game’s real story campaigns, and they’re why replaying the same country three times produces three different wars.
• Division Templates & Equipment Designers: You don’t pick from a menu of units — you build them. Battalion-by-battalion division composition, then custom tank hulls, plane airframes, and ship layouts with tradeoffs in reliability, cost, fuel draw, and combat width. It’s the crunchiest theorycrafting layer in the genre.
• The Battle Plan System: Draw arrows on the map, assign an army, hit execute, and your generals carry it out with planning bonuses that reward patience. It’s the single best onboarding concession Paradox has made to the front-line micromanagement problem — and also the system most likely to frustrate when the AI decides a general needs to walk his entire army across Ukraine.
• Supply, Fuel, and Attrition Modeling: Post-No Step Back, logistics is a first-class citizen. Railways, supply hubs, motorization, and truck throughput now determine whether your armored spearhead reaches Moscow or stalls in the mud with black supply icons. This is the update that made the game actually about what WWII was about.
• 32-Player Multiplayer and a Total-Conversion Modding Scene: Kaiserreich, The Great War, and Millennium Dawn are full games bolted onto HOI4’s engine — a Central Powers-victorious 1936, a WWI simulator, and a modern-day geopolitics sim respectively. The Workshop is not a side dish here. For a large share of the playerbase it’s the main course.

The Gameplay Loop

The loop is simple to grasp and effectively infinite. Pause. Read. Decide. Unpause. Watch the consequences arrive at 1x, 2x, or the reckless 5x speed. Pause again.

In the first hour of a campaign you’re doing economics: converting civilian factories into military ones, signing trade deals for rubber and tungsten, choosing research slots that won’t pay off for three in-game years. It is a spreadsheet with a swastika-shaped deadline, and it’s compelling precisely because every decision compounds. Build too many civs and you’re rich and defenseless in 1939. Build too many mils and you’ve frozen your industrial ceiling. The game never tells you which mistake you’re making. You find out in Belgium.

Then the war starts, and HOI4 changes genre. The land war is a war of frontage and combat width — a puzzle about pushing more organization into a tile than the defender can absorb, then exploiting the breakthrough before their reserves plug the gap. It rewards understanding, not clicking. Good players win by having built the right divisions in 1937, not by micromanaging in 1941.

Where It Gets Opaque

Here’s the honest criticism, and it’s the one that shows up over and over in the Steam reviews: the naval and air layers are markedly worse-explained than the land war. Naval combat resolves in a black box of detection rolls, positioning, and screen-to-capital ratios that the UI barely surfaces. You lose a fleet and the after-action report tells you what died, not why. Air warfare is similar — you assign wings to a region, set a mission, and hope your efficiency numbers trend the right way. The systems underneath are real and reasonably well-designed. The communication of those systems is not, and that’s a design failure, not a skill issue.

Onboarding Friction Is the Central Problem

The tutorial exists. It is not sufficient. HOI4’s honest onboarding path runs through the wiki and a YouTube channel, and Paradox has been unbothered by this for ten years. There’s an argument that the complexity is the product — that filing off the edges would produce a lesser game — and there’s something to it. But a decade in, the tooltips still nest four layers deep, critical numbers still hide behind hover states, and there’s no in-game explanation of why your 40-width tank division is or isn’t good. The community built that knowledge base. Paradox benefits from it without having built it.

The AI Is the Weakest Link

Let’s be blunt. The AI mismanages fronts. It stacks divisions where they’re not needed, leaves coastlines naked to naval invasion, and can be pulled apart by any player who has learned the standard exploits — a single-division port grab, a paratrooper drop behind an unprotected line, an encirclement it walks straight into. Against a competent human, HOI4’s systems sing. Against the AI on default difficulty, an experienced player is playing a logistics game with a scripted opponent. The difficulty sliders help; they don’t fix the underlying behavior.

The DLC Question

You cannot assess this game honestly without addressing the price architecture. The base game is a $49.99 premium release and frequently on sale. The full experience is not cheap. The expansion list is long, each one reworking or adding content for specific regions and mechanics, and the practical result is that a new player looking at the store page sees a wall of add-ons and a total that dwarfs a typical premium release. Paradox now offers a subscription bundle, which is a real mitigation and also an admission that the à la carte model got out of hand. Free patches do land alongside every paid expansion — that’s the deal, and it’s a better deal than most live-service games offer — but the entry-point sticker shock is real and it deserves the criticism it gets.

The aesthetic is functional, and that’s meant as a qualified compliment. HOI4’s map is a beautiful thing when zoomed out — a clean political view with sharp borders, moving unit counters, and a day/night terminator sweeping across Eurasia. Zoom in and the 3D models are serviceable at best; these are not assets anyone bought this game for.

The UI is where the real critique lands. It’s dense, gray, and heavily reliant on iconography you must memorize. It has improved — the newer designer screens are well-laid-out — but the older panels betray their 2016 origins, and the whole thing is a patchwork of design eras stitched together by successive expansions.

Performance is the perennial complaint and it is legitimate. Late-game slowdown is not a bug, it’s a structural consequence of simulating hundreds of nations, thousands of divisions, and every unit’s supply state on what remains a largely single-threaded tick. By 1944 in a full world war, 5x speed becomes aspirational. A fast single-core CPU matters far more than the GPU here, which is an unusual thing to say about a 2016 game in 2026.

This is a Steam-native, mouse-and-keyboard experience, and it makes no apologies. Windows, macOS, and Linux. No console port, no mobile version, no Switch release — and given the design, that’s clearly not stubbornness. There is no plausible gamepad mapping for a UI with this many nested panels and hover-dependent tooltips.

Steam is doing heavy lifting beyond distribution. Workshop integration is the game’s second life — subscribing to Kaiserreich is a two-click operation, and mod-enabled multiplayer lobbies work well with the launcher’s playset system. Steam’s own achievement layer has also become a de facto challenge mode; a meaningful chunk of the veteran playerbase treats the more absurd achievements as the actual endgame content. The 32-player multiplayer runs through Steam networking, though desync in heavily modded large lobbies remains an occasional headache.

On macOS and Linux the game runs, but it’s the second-class experience — Mac users in particular report performance below Windows parity on comparable hardware.

Hearts of Iron IV is an ambitious, ill-tempered machine. It asks more of you than almost any game on Steam and gives back proportionally — a simulation with enough moving parts that experienced players still find new interactions a thousand hours in. The focus tree system addresses grand strategy’s replayability problem better than any competitor has, and the supply overhaul turned a game about arrows on a map into a game about the thing that actually decided WWII: whether the trucks arrived.

It’s also a decade old, showing it in the UI, hobbled by an AI that can’t fully use the systems built around it, and wrapped in a monetization model that turns one purchase into a long conversation. Those flaws are structural, not incidental, and Paradox has had ten years to address them.

We recommend it on sale, to the right audience. Budget for one or two expansions, not twelve. Set aside a weekend, accept that the first three campaigns will end badly, and understand that the wiki tab is part of the interface. What’s on the other side of that wall is a rewarding strategy game — it just has no interest in meeting anyone halfway.