Hearts of Iron 4 review

Hearts of Iron 4 is the single most challenging game I've played in the last decade.

Hearts of Iron 4 is a grand strategy wargame from Paradox Interactive, makers of famously complex titles like Crusader Kings, Europa Universalis and, most recently, Stellaris. But unlike those other games, Hearts of Iron 4 isn't a sandbox; it's a game deeply rooted in the real history of World War II.

Hearts of Iron 4 has challenged me at a foundational level. But I don't mean "challenged" in the traditional sense. It's not hard like a roguelike is hard, and it's not difficult in the way that a flight simulation or a hardcore shooter is difficult.

Instead, Hearts of Iron 4 has challenged what I know about history, about military strategy and about mid-20th-century geopolitics. With Hearts of Iron 4, Paradox has dared to allow players to feel stupid. It's a gamble that pays off.

Starting a game of Hearts of Iron 4, players are able to choose from two distinct modes. The first, beginning in 1936, allows players to take control of any of the major Allied or Axis powers and captain their economic and political development in the years leading up to the onset of hostilities. The second, beginning in 1939, picks up the story on the eve of war and is much more focused on action and conquest.

But Hearts of Iron 4 goes a step further, allowing players to take control of nearly every single nation-state in the world during the same time period. If you want to play as Eleazar López Contreras, a Venezuelan fascist with two army divisions and 12 fighter planes to his name, you can give it a go.

The advantage players have of choosing the major powers, however, is a meticulously crafted tree of National Focuses that allow you to change the course of history on a whim.

Would you like to try and make France go Communist? How about changing Britain's foreign policy with regard to the Balkan states or Poland? What if the United States took a firm stance against Britain, came down hard against imperialism and invaded Canada?

The National Focus system turns this historical wargame into a kind of role-playing exercise, where players are free to go down paths never dreamed of by historians. Better yet, it gives you all the tools you need to direct a nation's industry and economy toward those ends.

In Hearts of Iron 4, you're not just the commander in chief of the armed forces. You're in charge of diplomacy, economics and production on a monumental scale. Given the right prerequisites, you can choose to strengthen your navy or air force at the expense of all other branches. Want to find out what would happen if Germany discovered atomic weapons in 1944? There's a path for that. And, for the rivet-counters out there, Hearts of Iron 4 even allows you to pick and choose which model of tank you want to roll off the assembly line, and where you want to send them to support your units in the field.

But with all this flexibility comes an almost inconceivable amount of micromanagement.

Take, for instance, the feature whereby individual factories must be dedicated to the production of discrete weapon systems. Those factories will get better over time, creating rifles more quickly and cheaply. So while a new rifle might be more effective on the battlefield, will that increased killing power outweigh the benefits of a lesser weapon manufactured in greater numbers? The only way to find out is to make a decision, and live with the consequences.

But while all the buttons and levers are there for you to play with, what Hearts of Iron 4 lacks is any sort of artificial intelligence to support your economic and industrial decisions. Armies will form up along a front line, generals will follow orders to attack on the day and time of your choosing, but on the homefront, players are on their own.

There were times when I wanted help manage all the behind-the-scenes decisions required to play Hearts of Iron 4, but there was no one there to save me. To start a campaign is to submit to Hearts of Iron 4's intrinsic and at times crushing burden to absorb arcane historical knowledge, to eat it for breakfast, lunch and dinner.

There are no training wheels here, and to avoid embarrassment, I quickly became a student of things like signal companies, period radar systems and advanced cryptography.