I first discovered They are Billions a few months back, but even then I was pleasantly surprised by a few things: the level of polish, especially for a game still in development; the easy-to-understand yet complex-to-execute rules that directed the building of your colony; and the difficulty. There may be billions, but all it takes is one misplaced zombie to turn most of a colony into a screaming horde of flesh-eating maniacs.

I got hooked quickly and lost countless hours trying to come up with the best strategy to defend my base. I lost many rangers, soldiers, colonies, and a whole lot of sleep trying to fend off the hordes of ravenous undead. It was a rollercoaster of emotions, from excitement at the sight of the final wave to frustration when my three-hour-old colony got crushed, and triumph as I finally beat the first map.

It's easy to become frustrated and feel like They Are Billions' survival mode is impossible to beat unless you're a StarCraft veteran or some insane mutant keyboard ninja, but I’m here to give you a few tips and points on how yours truly managed to defeat it.

Use the pause button to think 

Don't worry about destroying your spacebar as you frantically pause and plan your next move. Use this time to check the calendar to know how much time you have left before the next wave. Never leave a portion of your base unattended, use the patrol move (the shortcut is P) on your units so they cover the most area, and to be sure no zombie can pass through your defenses. 

Slower zombies roam the interior of the map, so they're easier to catch with your speedy Rangers. But don’t forget that special infected roam the northern and southern side of the map. If possible, expand to the east or west first to avoid activating them too early.

Expand to focus on generating gold 

You're going to need billions to defeat Billions. Gold is used for everything: units; research; buildings; defenses. You'll need not just a big bank (through Warehouses, which store gold and resources), but a strong income rate to allow you to recover quickly. 

Treat land as gold. With more land you will have more food and therefore be able to build more houses. You need to expand early. If your Rangers spot some free stone on the map, save it for a Soldier Center—more units means more area you can own and protect. As far as research goes, if you don’t have good food revenue you should aim for Farms first (if your first mayor offers you Farm tech, elect them immediately), otherwise aim for Cottages first.  

Urban planning 

The very first thing you want to build is either a Fisherman's Cottage or a Hunter's Lodge, depending on your starting position. You'll need the food. Follow that by dropping seven Tents to get your worker numbers up, and also so you hit the first mayoral election as soon as possible. Make sure to leave room on the green grass for Farms.

The Market and Bank buildings should literally be at the center of your housing so plan for that from the start. The Bank increases the gold output of surrounding buildings while the Market reduces the food cost of anything in its radius, and you should build a massive, dense housing district around them. You can only have three such districts so plan carefully on where you will put them for maximum efficiency. Markets also let you sell excess resources and though they'll do so automatically, it's more efficient to do so yourself.

Don’t build advanced buildings if you can expand and find resources elsewhere. Most of the time their steep upkeep cost will only hurt your economy.

Rangers early, Thanatos late 

Tiptoe in the early game but be ready to rumble in the late game. Zombies look so inoffensive with their low pool of HP and slow shuffling, right? Wrong! They are lethal death machines that will swarm you. Some of them can run, some of them can hop over walls, some even spit splash-damaging acid. In the early game you don’t want them banging at your door and so you want to make as little noise as possible. Thankfully, humanity have given you the perfect tool for this job: the Ranger. Armed with a bow and arrow they deal with the infected threat as silently as possible. The Sniper is also a viable option, but they generate much more noise, and will eventually attract lots of undead if they're firing often. Be especially careful around a Village of Doom—the ghastly haunted houses that contain a large but finite amount of undead—as an early army will not prevail.

Once you've built up a reliable defense, put together a mobile fighting force for clearing the map. I like a mixture of Rangers, Snipers, and Thanatos, and a Titan or two if you're economically booming. You can hit the C key to command these units to 'chase,' or seek and destroy any and all zombies on the map, though you'll still want to micromanage your forces, as they won't do much to arrange themselves intelligently. It's important to clear as much of the map as you safely can before the final wave, where any spare undead will join the finale. Map hygiene might make all the difference.

Layer your defenses 

Never neglect your defenses. You think that this massive wall protected by a plethora of Executors and Ballistas will be enough? Think again. Assume the worst, and focus on reinforcing your weakest points first. Always layer your base and use chokepoints to organize those layers. By the final wave, zombies coming from any direction should encounter at the very least three layers of stone walls protected by Executors. 

Executors are your best pals. Build them everywhere. Don’t get tempted by the Shocking Tower, which costs tons of energy and won't give you the DPS you need in the endgame. Consider spike traps as a luxury, too: they're resource-intensive and not durable enough to be of much use. Ballistas are all good in the early game and have the advantage of being upgradable to Executors. But in the end, Executors are your BFFs, paired with layers of stone wall. Build them everywhere, pause the game when there’s a breach, and delay the horde with layers after layers of walls. Only then will you prevail.

The steampunk zombie survival RTS They are Billions has become a sensation over the new year break. You build bases, suck resources out of the terrain nearby, and then produce as many soldiers as you can to withstand the increasingly fervent attentions of the zombie hordes nearby. Instead of hunting down an enemy base, all you have to do is survive to win. Sounds easy, doesn't it? It's not. It's horribly, horribly hard.

As the game kicked my ass repeatedly earlier today, I was reminded of a few different games that have toyed with this formula before. It looks like an RTS, thanks to the base building and unit production, but plays like a tower defence game. Here are a few other good games that explore this curious in-between space, mainly by throwing thousands of bad guys at you.

StarCraft 2: Wings of Liberty

If you want to hold off hordes of enemies as they run riot through your base, then the Terran vs. Zerg singleplayer missions in StarCraft 2: Wings of Liberty are a good choice. In Haven's Fall the Zerg move to infest human settlements as your Terran army tries to stop them. In Outbreak you start surrounded by zombified settlements that vomit out hordes of aliens every time night falls—sound familiar? StarCraft 2 marines look pretty similar to your basic gun troops in They are Billions, and TaB's watchtowers are basically StarCraft 2 bunkers.

Desktop Tower Defense

There is a strong tower defence element to They are Billions. Waves of creeps attack from different directions and mindlessly throw themselves against your defences until you or they are toast. Most tower defence games, like Defense Grid: The Awakening, funnel creeps into a set path that you cover with gun turrets. Desktop Tower Defense and They are Billions share a more open format. In both games you funnel the creeps into kill zones using the most efficient unit/tower placement you can invent. DTD has an advantage because it's free and you can play it in your browser.

Revenge of the Titans

Revenge of the Titans features giant city-wrecking Pac Man ghosts instead of zombies but, deep down, they hate the living all the same. This wave defence game has a much more developed resource system than Desktop Tower Defense, and you can place buildings with a bit more freedom than games like Defense Grid. Plus it has satisfying lasers that you can control with your cursor.

Infested Planet

Another RTS about fending off thousands of enemies at once, Infested Planet sets your desperate last stand on a luminous neon world swarming with hundreds of alien creatures. You command a squad of five marines on a desperate mission to find a chokepoint and throw down some turrets. If you hold off the horde long enough you can start to spend resources and upgrade your squad's weapons. Look out for the hives nearby—they spawn increasingly tricky monsters as you fight through the campaign.

Project Zomboid

Project Zomboid is a survival game rather than a RTS game, but you're still gathering resources, building defences and fending off massive hordes of zombies. Death is inevitable, but it's the horrible, lingering journey full of disease and suffering that counts. Project Zomboid has been receiving new features since its Early Access debut in 2013, and has evolved into a deep, clever sandbox game that, like They are Billions, will kill you ruthlessly over and over.

Death comes as a sudden, unpleasant surprise in They Are Billions. It's a real-time strategy game strongly reminiscent of late-'90s classics like Age of Empires or StarCraft, but rather than a symmetrical battle against other civilizations, you struggle against a horde of mindless zombies. The slightest breach in your defenses can mean that your base is infected, causing an explosive—and usually game-ending—surge as the zombies convert your helpless citizen residents into more zombies. A single shuffling zombie that sneaks past a poorly placed wall or into a new expansion can lead to a snowball that rolls over your entire base before you know it.

Director Jesús Arribas took the time to speak with me about what led Numantian Games to make a game about a zombie plague, as well as how their own viral growth ended up getting out of hand.

Questions and answers have been edited for brevity and clarity.

PC Gamer: They Are Billions is quite a departure from Numantian's previous game, Lords of Xulima. That game was a very traditional role-playing game in the vein of Might & Magic and Wizardry. How did Numantian Games go from straight-laced fantasy to this offbeat survival strategy game?

Jesús Arribas: They are very different themes and genre, but if you play both, you can see the same author’s touch, like the same painter who draws two different scenes.

Real-time strategy games have followed a similar trajectory as RPGs. The classic titles were very challenging and hard to master. You had the freedom to play the missions the way you liked. You were free to lose if you made stupid decisions. But at the same time, when you won, it was very rewarding. We have always been fans of RPGs and strategy games. We tried bringing back that feel of the old-school RPGs to the present with Lords of Xulima.

We have the same goal with the RTS genre and They Are Billions. You have to manage the economy and the resources, expand the colony, build an army, attack your enemies to clear areas, reach new resource sources, and of course, defend your base from the infected hordes. And this is just the Survival Mode. We are working on the Campaign which is a bit more similar to classic RTS, with a big story, tactical missions, and much more content.

Losing in They Are Billions happens very fast. Any failure means zombies convert your built-up resources into more zombies very quickly—and you even warn players about this threat. Why does They Are Billions have such a sharp death spiral into failure and game over?

JA: In this game, the zombies are not just an excuse to have an enemy to fight—they are the central pillar of They Are Billions. This is not about killing enemies. This is about combating the infection—the same infection that destroyed the world and is the main threat to the new survivors. You could have a massive colony and suddenly find it in ruins because of a single infected breaking through. Fear and danger are constant.

The infection is the real threat to the survival of the colony. We know many players can get frustrated because of this. There is no other game like this. So, when a player loses their first colony because of a single decrepit zombie, they can hardly believe it. It is part of the fun. Nevertheless, a full game can last 2-3 hours if you survive all the way to the end. It is a game about surviving and improving your survival skills, not winning. If your score gets higher every time you play, then you are doing great.

Most developers tend to think that they must take care of the players, that they need everything easy and straightforward. But we don't. Players are much smarter than we give them credit for. When they are challenged with a game like this, where there is no hand-holding at all and even losing is fun, they actually love the experience.

Shooting zombies can fit into all sorts of settings, from traditional high fantasy to far-future science fiction. Why steampunk? What about Victorian aesthetics made them feel like a good fit for a survival game?

JA: From a development point of view, we thought that it would be super interesting to mix a steampunk society with their low technology with a zombie apocalypse. Watching the Titan, a steam machine driven by an educated gentleman with Victorian manners, destroying zombies is something worth experiencing.

Because it is set in the future, the 22nd century, one may question, "What has happened to the civilization and the modern world? Why has technology gone backward to a 19th century level? Where did the zombies come from?" You have to play the campaign to find the answers. 

A significant departure from Numantian Games' previous work is the shift from crowdfunding on Kickstarter to launching straight to Steam Early Access. Why didn't you head to Kickstarter a second time? 

JA: Instead of launching a Kickstarter, which requires months of work and preparation, we decided to do something softer and just to launch a campaign directly from our official Numantian Games website. We thought that it would be a great idea to let the backers play the Survival mode to collect feedback and test the game, [so] we then added Steam beta keys to the rewards and released the [crowdfunding] campaign on Halloween. 

And what happened? People started to purchase the game, play it, and upload videos to YouTube. The game went viral very fast. So fast in fact, that we ran out of Steam beta keys in one week for the lower tier, then in a few days the next tier, and so on... 

In two weeks, we ran out of beta keys—we originally had 10,000. We asked Valve for more beta keys, but we were unable to acquire any more keys until we released the game on Steam. We ended up in a situation where big YouTubers were playing the game, but people were unable to purchase and play it as well.

We made the decision to release the game with just the Survival Mode on Steam Early Access. Then we could work on the main game mode, Campaign mode, during the Early Access phase. We had to release the game about six months earlier than what we would have liked. Fortunately, the launch on Early Access has been very successful. We are still on the top seller list since the launch, the comments and reviews are very positive.

Where do you plan to go from here? What's your first priority to add (or fix) in the near future? What are your goals before leaving Early Access? And what are your plans once They Are Billions reaches 1.0?

JA: We are working in parallel on two different fronts. First, solving bugs and fixing problems and hardware compatibility issues. And second, making the game multi-language. Our goal is to have the game in eight languages in just a few weeks. The game is selling well all over the world, so we want as many players as possible to enjoy it in their own language.

After that, we are working on more features for the Survival mode, new buildings and zombies. [Another upcoming new mode is] Challenge of the Week. In that challenge, all the players can compete for getting the highest score playing the same survival map. We think it will be very funny as even the developers will participate in the challenge every week.

Finally, we continue working on the campaign. Thanks to the success of the game we can invest more in creating a memorable and epic campaign. Stay tuned!

They Are Billions is currently available on Steam in Early Access.

Tim Clark: Simulacra  

Look, I'm nothing if not entirely predictable, so to the surprise of absolutely nobody, least of all myself, I failed to catch up on Assassin's Creed: Origins. To be fair I did boot it up and made it through a couple of missions, but as I saw its vast sandy expanse stretching away into the distance, I felt the clarion call of my old favourites. And so most of the break was spent grinding Destiny 2 for masterworks weapons, of which I now have an indecent amount, but somehow still no raid hand cannon. I also managed to crank out a successful Hearthstone Dungeon Run with every remaining class, thereby earning the card back. Shaman was the last to fall, and finally got over the line last night—but only after I started auto-quitting unless I was able to get the 'double Battlecry' passive buff and a decent batch of Jade cards.

In at least a slight change of pace, I did play most of my games on a laptop this Christmas, a gift from my family and myself to myself. Being able to plug the 1070-equipped ASUS into the bedroom TV and enjoy Destiny 2 at 1080p/60fps made for an illicit pleasure and long lie-ins. (I also ended up buying a wireless adapter and charging pack for the Elite controller.) And at least I managed to play one entirely new game stuff on the laptop. Inspired by Hannah Dwan's retrospective on 2017's best visual novels, I picked up Simulacra and finished it over the course of a couple of nights on the sofa with my other half.

This was the first 'missing phone' game I'd tried, and I loved the mix of stalker-themed Tinder mystery with weirder supernatural trappings. Creeping around the emails, Twitter account and chat logs of a girl who has disappeared becomes propulsively dramatic when a blizzard of new notifications start popping up. Simulacra doesn't quite stick the ending, but as a self-contained mystery it was still a great way to spend a few hours. You can pick it up on Steam in the Christmas sale right now at 30% off.

Steven Messner: Path of Exile

I had great, ambitious plans for this holiday break. With a back catalogue of games that had grown considerably over 2017, I was looking forward to making a big dent while sipping rum and eggnog in my underwear. I was going to finally wrap up Persona 5. I was going to try out PUBG’s new desert map. I was going to shovel the walks like a good neighbour should. And then I logged back into Path of Exile to give the new seasonal league a quick taste. I fell in love with the free-to-play ARPG back in September with its Fall of Oriath expansion, but I was curious about seeing how it had grown since then. Nearly two weeks later, I’m looking back at my holiday break in despair. Where the hell did it go?

It’s been years since a game has wormed itself so deeply into my brain, but Path of Exile is like a fever that won’t break. I’m not exaggerating when I say that I woke up exhausted more than once because of a restless sleep filled with dreams of running maps, finding exorbitantly expensive unique items, and theorycrafting my build. I clocked in over 60 hours this holiday break—an average of five hours a day (though I’m ashamed to admit there were a few days where it was much more). Path of Exile consumed me. I’m finally willing to say that it might even be my Dota 2, the game that I will happily clock a thousand hours into and countless more talking and dreaming about.

Tyler Wilde: Civilization VI 

I uninstalled all my Civ 6 mods (some old, manually-installed mods were breaking all the icons and I couldn't remember which) and relegated half of New Year's Day to building a prosperous Russian civilization. I quit in the Classical Era to go find my old mods, though, disappointed by how few quality of life improvements have been made standard so far. Still no production queue? A strange omission. That aside, I still love Civ 6's district system, as I always thought it was silly that a city near the ocean couldn't have a harbor, and city-planning minutia is my favorite aspect of the series. 

Building mines, farms, camps, and roads, protecting caravans, erecting wonders and ensuring that every district is placed exactly where it out to be, maximizing gains—these are the reasons I play Civ, not warfare, so I'm typically on the defensive, protecting my perfectly symbiotic metropolises and hamlets from the absurd imperialist reasoning of my neighbors. Presently, Mvembra a Nzinga is furious that I won't spread my religion to his people, and Qin Shi Huang is upset that I've built more wonders than him. What did my peaceful, overly efficient society do to deserve such petty neighbors? Yet again I wonder if I wouldn't enjoy Civ more if I were by myself in the world.

Evan Lahti: They Are Billions 

Some of the most fun I had with RTSes as a kid was messing around with Command & Conquer: Red Alert's map editor. I'd make winding tesla coil death mazes that my opponent had to navigate in order to reach my spacious, well-supplied base. They Are Billions revives that same feeling of defense-focused strategy, except I'm the one being tortured.

The structure of it is somewhere between StarCraft and a horde mode game like Killing Floor 2: you expand outward with pylon-like towers, hoovering up wood, minerals, and food off the map to feed your economy, but there isn't a true opponent on the map with you—you're the only one with an expanding base. Instead, there are crowds of mostly stagnant undead (with various durabilities, speeds, and attack types) occupying the map, and massive waves of them that attack every 15 minutes or so from a random direction.  

I love the preparation for the payoff at the end, a Left 4 Dead-style finale where actual thousands of zombies are on screen simultaneously, seeping in from all cardinal directions. Your north wall may be impregnable, but did you gather enough resources to reinforce that bottleneck to the west? An Early Access game, They Are Billions needs a little more depth and unpredictability in its midgame, but it nails the fun of building a sprawling defensive death machine and having it continually tested by a tough enemy.

Chris Livingston: Rick and Morty: Virtual Rick-ality 

I finished Rick and Morty: Virtual Rick-ality before the break, but despite its size (it mostly takes place in Rick's garage and only gives you three spots to stand in) it's a impressively expansive VR playground. This is mostly to do with the Combinator, one of Rick's inventions that allows you to put two items onto it and see what you get when they're scientifically merged (think of Jeff Goldblum and a fly getting into a teleporter together). 

Often it's nothing exciting (combine a glass with a bar of soap and you'll get a bar of soap made of glass) but there are enough weird and surprising combinations to make you want to combine everything with everything else, and then combine the resulting combinations with the resulting combinations. And then combine those some more. Throw in some growth pills and the fact that you can copy your own brain (by laying your VR head on the combinator) and you might, with enough re-combining, wind up with an enormous twitching brain that fills the entire garage.

And despite it looking like a cartoon, it's still the most convincing VR experience I've had. I almost fell over after trying to lean on a countertop that doesn't actually exist, I've punched a few real walls throwing things around, and I realized that when eating or drinking something in the game I actually open my (real) mouth.

Wes Fenlon: Thimbleweed Park and Zero Escape: Virtue's Last Reward 

My holiday gaming involved a lot of puzzle solving. Over Christmas I was away from home and my gaming PC, so I actually spent most of my time with friends playing games on Nintendo's SNES Classic and Switch. If you love XCOM, you really need to try Ubisoft's excellent Mario + Rabbids: Kingdom Battle. In the last few days of the break, though, I really dug into two games I've been meaning to play for months: point-and-click adventure Thimbleweed Park and escape room visual novel Virtue's Last Reward.

Thimbleweed Park is delightful so far, with classic adventure game puzzles that err on the side of reasonable instead of impossible logic. It gives you multiple characters to control so you don't get stuck and can jump between puzzles and areas at will, and there are also some clever bits that require using one character to help another. It's a little meta jokey for my taste (as mentioned in our review) with frequent jokes about the genre itself, but the laughs I've gotten from the ridiculously foul-mouthed Ransome the Clown have more than made up for it.

Currently, though, all I can think about is Virtue's Last Reward, which has its hooks in me deep. The central mechanic of this escape room game is solving the mystery of your imprisonment, with every major decision you make creating a new branching path—but you can go back and take a different route whenever you want. Information you gain from some dead-ends actually lets you progress down paths that don't end with horrible suicides, explosions, or deaths by lethal injection. The way it teases out the solution to its mystery is maddening, and there's a bit more repetition of similar conversations than I'd like, but I need to find out what happens, and each cliffhanger I hit just adds fuel to the fire.

Andy Chalk: Hob 

I started playing around with Hob shortly after it came out in September, but I didn't make a concerted effort to really do anything with it until the holidays arrived. With time on my hands, I got down to the business of properly exploring the bizarre, wild mechano-landscape, collecting its secrets, and unraveling the great mystery that lies beneath. Most of my gaming time is dedicated to shooting dudes or playing roles, but this odd little diversion ("little," I say, as Steam shows 36 hours sunk into it) was nothing less than magical: Complex without being obtuse, challenging but never punishing, and set in one of the prettiest and most unusual game worlds I've ever explored.

The platforming is a tad wonky at times but never unfair, and more importantly the sights and sounds are so wonderfully weird that even after botching an obvious and simple move, I never felt the urge to pound my mouse into pieces with my keyboard. The ending was brilliant, too. No spoilers, but there is a story being told amidst all the strange grunts and glowing hieroglyphics, and the payoff was unexpected—and unexpectedly difficult to process, too. For all that I loved the game world, the fact that Hob isn't just jumping and slashing its way to a simple happy ending might be my favorite part of the game.

Everything we said in our review was spot-on (although I would've scored it ten points higher—sorry, Other Andy) but I feel like it could stand to be shouted from the rooftops a little more loudly: Hob is a fantastically good game. (And Runic deserved better.)