A brutal blend of real-time strategy and survival horror, They Are Billions challenges players to build, fortify, and defend a burgeoning colony against unrelenting hordes of the undead. At once cerebral and nerve-rattling, this game pits you not just against zombies, but against the ticking clock of survival itself — and very few other strategy titles capture that tension with such relentless intensity.
Originally launched to critical acclaim on PC, They Are Billions later spread to consoles and, in 2026, received a polished Nintendo Switch and Switch 2 version that brought its unique brand of frantic base-building to handheld play. In an era where strategy games often lean toward accessibility and calm planning, They Are Billions refuses to compromise: order must be built, walls must be thick, and every decision — even the smallest — can be the difference between survival and annihilation.
A World on the Edge of Extinction
Set in an alternate steampunk timeline, They Are Billions begins with humanity driven to the brink by a global zombie pandemic. Scattered pockets of survivors cling to existence behind wooden palisades, cobblestone walls, and makeshift defences. Your job, as a colony commander, is simple in concept and punishing in execution: establish a foothold, grow your settlement’s economy and infrastructure, and withstand wave after wave of undead assaults that steadily grow in size and ferocity.
Unlike many RTS games where combat is a feature, in They Are Billions, survival is the game. There’s no winning by conquest, only by endurance — and if your walls fall, the zombies don’t just overwhelm your soldiers… they overrun your entire world.
The Brutal Beauty of Survival Strategy
At its core, the gameplay loop of They Are Billions is a careful balance of economy building and defensive preparation. Each settlement begins with a handful of workers, a Town Hall, and minimal resources. From here, you construct basic structures like tents, farms, lumber mills, and sawmills to grow your population and economy. Soon enough, you’re managing stewards extracting gold, engineers building advanced technologies, and captains training troops to defend your wooden walls.
Economy and defence are forever in tension. Build too slowly and the incoming zombie waves overwhelm your perimeter. Expand too quickly without planning defences, and you’ll find gaps in your lines and breaches in your walls. The sense of constant threat is what keeps They Are Billions taut; there’s never a moment where you can relax completely. Even when skies are blue and workers cheerfully gather resources, you know that at any moment a scout report might signal a creeping horde.
This tension is not accidental; it’s excellent design.
Waves of the Undead: Fear by Numbers
The game’s titular feature — billions of infected — is no exaggeration in spirit. While individual zombies are slow and weak, their real power comes in overwhelming numbers. Early in a run, you might face only tens of undead — manageable with a few soldiers and sturdy walls. Mid-game, that can escalate to hundreds. Late in a campaign, waves comprised of thousands of ravenous bodies can descend upon your colony.
Combat in They Are Billions isn’t about flashy unit abilities or tactical micro-management on the scale of MOBAs or traditional RTS skirmishes. Instead, it’s about positioning, preparation, and layered defence. There’s a visceral thrill in watching a massive undead wave crash against your ramparts, watching your barricades crumble and your soldiers hold the line — or not. The engines behind these soul-crushing assaults are smart: zombies will attack where defences are weakest, and knowing how to funnel them into chokepoints is part of the strategic core.
When a breach happens — and it will — seconds feel like hours as you desperately send reinforcements, rotate troops, and pray your walls hold. Few games outside of survival horror can produce that level of genuine anxiety through strategic play.
Building a Colony That Endures
Economic management in They Are Billions is deceptively deep. Structures are not just built — they must be supported by roads, powered by steamworks, and connected to supply chains that make your city thrive. Resources include wood, stone, iron, food, and gold, each with its own gathering and transportation complexities. The more ambitious your colony, the more vulnerable its infrastructure becomes.
Planning is essential. A sprawling, inefficient layout can spell disaster when deadlines approach. Every building placement is a choice between growth and defensibility. Do you create a tight fortress at the start and risk resource bottlenecks, or expand quickly and push your defensive lines outward? They Are Billions constantly pushes you to answer this question, and most players will try both approaches (and fail many times) before finding what works.
There’s no “easy mode” in the campaign. The game opens with shorter missions and smaller maps to teach principles, but soon enough the objective is simply: “Last as long as possible.”
Presentation: Steampunk Grit and Grim Atmosphere
Visually, They Are Billions embraces a gritty, muted steampunk aesthetic. Workers in leather aprons churn away at steam engines; soldiers in rusted armour patrol ramparts; and the undead lurch through ashen fields under smoke-grey skies. It’s a world built from soot and desperation, and the art direction reinforces the feeling that every moment is a fight just to exist.
Interface design is smart and functional. On PC, mouse controls make city building precise; on Nintendo Switch platforms, touch and stick controls are implemented with care. Tutorials are clear, but players should expect a learning curve — steep but fair.
Sound design echoes the tension. Mechanical clanks of production buildings mingle with distressed shouts from soldiers and the guttural moans of approaching hordes. Music swells during critical moments, and at other times recedes into eerie silence, reinforcing the sense of cosmic dread.
Challenge and Replayability
If there’s one thing They Are Billions doesn’t lack, it’s challenge. Even experienced RTS players will find themselves overwhelmed again and again. The AI doesn’t cheat — it simply throws numbers at you until your mistakes become fatal. And there are plenty of brutal waves that arrive mere minutes after your walls are up, forcing you to always think two steps ahead.
Beyond the main campaign, the game offers a “Survival Mode” with randomised maps and enemy spawns. Here, the fun lies in adapting your strategy on the fly as every run presents new terrain, resources, and threats. This mode alone adds enormous replay value, making every failure an opportunity to learn and refine tactics.
Where It Falters
They Are Billions is thrilling, but not without flaws. The steep difficulty curve — part of its identity — can feel punishing to newcomers who prefer strategy with gentler ramps. Some users may find the campaign’s mission variety limited: defend here, survive there, fend off a mega-wave over there. While the tools you use change with tech unlocks, the core tasks remain repetitive.
A few technical issues have been reported on console ports — occasional framerate drops in massive late-game hordes, and UI navigation that feels more natural with a keyboard and mouse — but these rarely detract from the overall experience.
Verdict
They Are Billions is an uncompromising survival RTS that marries base-building with sheer terror. It doesn’t hold your hand, and it doesn’t apologize for its difficulty. Instead, it rewards players who enjoy careful planning, adaptability, and the electric dread of watching tens of thousands of undead march against your defences. Few games inspire that level of fear mixed with triumph.
If you crave strategy with stakes that feel real, and you don’t mind dying repeatedly on the path to mastery, They Are Billions is one of the most exhilarating experiences in the genre.
