Democracy is on the brink of collapse. Caesar’s Legion, the authoritarian slave state across the Colorado River, has launched a massive assault on the last, best chance for freedom in the post-apocalyptic world of Fallout. It’s a grim certainty in Old World Blues that the New California Republic will fight Caesar’s Legion: they’re the wasteland’s two superpowers, diametrically opposed ideologically, each expanding towards the other. I just thought I was better prepared. While Caesar was annihilating every ill-defended tribe to the west, I was rearming, inviting new states into the republic, and admittedly annexing a few tribes myself. With the game paused, I assess my options, reorganise my armies and ask, finally, does democracy die in 2279?

Old World Blues is a mod for Hearts of Iron IV which transports the World War II grand strategy game hundreds of years forward into the post-apocalyptic American west coast of the Fallout series. Players select a faction in the year 2275 and attempt to survive and thrive in the west coast wasteland. Structurally, it’s similar to Hearts of Iron IV, but the content and style has been transformed. Old World Blues is tremendously fun, comparable in quality to the standard Hearts of Iron IV game, and it does a terrific job of translating Fallout to grand strategy.

Currently, nine factions in Old World Blues have unique focus trees – that is, their own web of events to navigate – mainly those with a role in an existing Fallout game. The variety among these nine is impressive: unconstrained by the need for historical accuracy, the mod team have done a stellar job of making each unique, with their own divergent focuses, types of unit, researched technologies and crises. Many of them have their own faction art, character pictures and voice lines.

When I started a game as Vault City, I was surprised to find I had only one unit of infantry to defend my borders against the five surrounding tribes and an extremely shallow pool of manpower with which to train more. However, almost as soon as a Vault City campaign begins, you’re confronted with an irreversible event that decides its future. Ghouls, the city’s oppressed underclass, take up arms in rebellion.

Simultaneously, The Brain, a giant evil rat, attacks the city with an army of mutants. Vault City’s leader, its national spirit, and what national focuses it can select in the future are determined by who wins.

Every available option has its own ways of marshalling more troops or making your standing army, the poorly equipped descendants of vault security, more formidable. The Brain can breed mutants to fight for him or abduct the residents of neighbouring tribes for experiments and the ghouls can mobilize new migrants. I chose to maintain the status quo as the lesser of three evils and the greater of three bonuses – a bonus to research and the potential to get even more.

Vault City begins the game as an isolationist, hyper-advanced society with a disdain for wastelanders. By maintaining the status quo, I reaffirmed this: the discounts to research allowed me to jump ahead of time to get advanced weapons and robots early. When I accessed population controls, which loosened the requirements for Vault City citizenship, I could finally grow my army.

Due to my advanced research I overestimated my troops’ abilities versus the apparently crude tribals around me. It was a very Vault City mistake to make, and it ended with my civilization being wiped from the map. I declared war on the Yakuza, my enemy to the south. Initially, my robot armies and advanced weapons made short work of the more conventional tribal warriors, but as I advanced my manpower reserves dwindled to nothing. Even though the Yakuza were losing more men per battle, each of their causalities meant less. They could replace troops, I didn’t have any new recruits of my own. I was overstretched and under supplied. The Yakuza counter-attack annihilated my weakened armies and they conquered all my territory.

As well as making for thrilling play, the diversity of factions in Old World Blues encourages roleplay. I could have equipped Vault City’s armies with melee weapons which are as viable an option for your troops as laser rifles or traditional guns. Given that all the text in events, descriptions and the national focus tree alludes to Vault City as a civilization technologically superior to its rivals however, it feels immediately wrong to pivot to troops armed with knives, clubs and other junk. Vault City has a very particular identity whether it’s led by the elitist First Citizen Lynette or an intelligent rat. The game does a great job both of communicating that identity and of making me disinclined to betray it.

That is not to say Old World Blues is proscriptive. Not only is there a great deal of variety in how each faction can be played, some even offer choices about how the faction responded to events prior to 2275, when the game begins. As New Vegas, these choices are focused on how Mr. House responded to nuclear warfare: did he prioritize protecting the suburbs, or military industry? Did he use an old, stable operating system or a new but incomplete operating system to run the Securitrons? Which tribes did Mr. House invite to operate the casinos?

My greatest success in Old World Blues has been achieved when I’ve planned how I want my civilization to develop as opposed to making decisions as they arise. As New Vegas, I knew I wanted to invite neighbouring raiders the Great Khans and the Fiends into my inner circle, and ultimately replace zombie capitalist Mr. House with his subordinate Benny. The first goal was trivial to achieve, since it just meant picking the Khans and Fields over the canonically correct casino operators. Replacing Mr. House is only slightly more complex, though again your candidates are determined by who you invite into New Vegas during the game’s opening moments.

I was interested in Benny particularly because of the event listed at the end of his branch: The Nevada Pact, which allows New Vegas to head an alliance formed from a constellation of city-states like New Reno, the Desert Rangers and the aforementioned Vault City. Achieving this objective had mixed results. At the time that I completed it, the New California Republic and Caesar’s Legion were at war. The Rangers appear to have been allied with the NCR, but when my offer to join the Nevada Pact arrived they agreed. However, they were still at war with Caesar’s Legion so I was invited to help. The Nevada Pact, which the game contextualises as a way of avoiding domination by the NCR was, hilariously, dragged to war against their enemies the moment it was born.

I was saved from immediate extinction only because a tiny neutral faction occupied the zone between our territories and refused to let either side’s troops through. Inexplicably, months into the war the NCR decided to annex these neutrals which had the effect of giving Caesar’s Legion direct access to my territory, since they were already at war with the NCR. I was fighting for my life, intending to hold the Legion off until the NCR advanced so far into their territory they collapsed.

New Vegas’ unique robots the Securitrons are quick and powerful, but they’re also almost irreplaceable during wartime. Each unit costs 240 medium robot equipment which is both time-consuming to produce and expensive in terms of metal, fuel and electronics. In Old World Blues (as in Hearts of Iron IV) if you have an insufficient amount of a particular resource, you’ve got to trade the production of one of your civilian factories to someone else to get their surplus. However, civilian factories are also used to build arms factories (the things that actually build the robot parts) and repair arms factories that are damaged, so trading them away is risky. Shortly after the war started, I was trading away half my factories.

Deliverance came not due to the NCR, who spent the war in a stalemate, but because I managed to outflank the Legion. New Vegas is on the west side of the Colorado, accessible to Caesar’s Legion only by crossing at Hoover Dam. By sending my secondary army composed of human thugs and Great Khans south through the NCR, I was able to approach from the other side of the Dam and crush the attacking force.

These kinds of manoeuvers are not possible to the same degree in vanilla Hearts of Iron IV. Changes to the effect of terrain is one of the most dramatic made in Old World Blues. Since it takes place on one continent, North America, it’s not possible to ford wide rivers like the Colorado except at designated crossing points or to march your armies through mountain ranges. This has the effect of literally splitting the map in places and often makes it easier for smaller factions to thrive. An individual Securitron will beat a Legionary, but if the Legion could pour across the Colorado anywhere New Vegas would quickly have been surrounded and swamped, since Caesar’s Legion had five times my troops.

I encountered the same system to my detriment as the NCR. One of the NCR’s early focuses allows them to attack a group of raiders called the Scorpions, a necessary step both to securing the front line with the Legion and accessing the wealth of New Vegas. I positioned my armies on their north and south borders, confident of victory since the NCR dwarfs the Scorpions in size and military strength. I forgot to cover one crossing point of the river between us: the mistake likely cost thousands of lives, prolonged the war by months and hurt my manufacturing. Even though I made good progress advancing into the Scorpions’ territory, the gap allowed their armies to maraud around my cities, wrecking factories and killing isolated troops who hadn’t reached their army. I won at a needlessly inflated cost.

As the NCR the options on your focus tree will lead you to New Vegas but it’s up to you how you get there. You can delay it and pick focuses which allow you to incorporate tribes like the Baja to the south or race to Hoover Dam as fast as possible. In my first game, I focused on cleaning up my borders, admitting new states to my faction, and befriending the Brotherhood. Unfortunately, as the NCR you’re all but guaranteed to fight Caesar’s Legion, which is at never-ending war as it devours every tribe nearby. When I zoomed out from my defence-oriented nation focused on peaceful incorporation, I was staring at a gargantuan legion which had already made its way to New Vegas.

I had to annex minor factions for my own security. The Rapids, an apparently peaceful tribe, were the first receive a declaration of war. They bordered both the NCR and Caesar’s Legion so it was lucky they ended up as citizens of the NCR rather than slaves of Caesar. The Mojave Raiders I have even less reason to regret: they were working on a focus called ‘Terrorize Locals’ when I declared against them.

As I mentioned, I had every expectation of fighting Caesar’s Legion, I just didn’t expect their troops would be quite so good. My armies were larger than theirs, and yet almost as soon as they attacked they were pushing across the Colorado at our shared crossing points. My allies offered little help except to offer to lend-lease me useless basic melee weapons. In June they captured Dayglow, in July The Boneyard.

The NCR survived numerous crises: the invasion of the Scorpions, deadlock at the polls which led to the elevation of President Kimball, battles with the Mojave branch of the Brotherhood of Steel, and the loss of Hoover Dam. 2279 was the final year of its existence due to poor decision making. Specifically, I listened to the message at the start of the game which warned me that the AI were incompetent as the Legion and offered me the chance to compensate them with bonuses. If Caesar is touring his new conquests, building a palace in Shady Sands and a victory arch in The Boneyard, it’s because the NCR was led astray by bad advice.

Old World Blues is not finished. Admirably, however, rather than create an entirely playable world map with missing game components, the mod team have developed the west coast (the settings of Fallout, Fallout 2 and Fallout: New Vegas) to a very high standard with plans to expand eastward in the future. It’s a surprisingly successful translation of a series with no grand strategy heritage. Its factions retain the often cartoonish personality of the Fallout games; they’re impressively diverse to play and to play against. It succeeds at encouraging roleplay and challenges players with a few strategic problems absent from Hearts of Iron IV such as the impassable terrain features. It’s among the best mods for Hearts of Iron IV, and a successful and creative marriage of a series and a new genre.

You can download Old World Blues from the Steam Workshop. For more great mods, check out our guide to the best Fallout 4 mods.