Zombie games are passé now. Years of seeing them featured in numerous games with little to no variation in their behavior has rendered them unexciting. Some may consider titles that feature zombies to be boring and trite. Real-time strategy games are just as numerous, but they've shown large differences from title to title, making most of them feel distinct even if the subject matter and tactics are similar. Combining them seems like a logical thing to do, and such an endeavor should yield something decent. However, with its lone gameplay mode for Early Access, They Are Billions makes it into something wildly addicting.

That lone game mode is Survival. As the name implies, it tasks you with trying to survive until the time limit is reached or your base has fallen, whichever comes first. Players are dropped in a randomly generated map, and while their main goal is zombie defense, the other equally important goal is the maintenance of the colony you're assigned to protect. There's a constant need to get resources to bolster your defenses and ensure your colony can survive between those attacks. Food, lumber and oil are all outside of the colony, and since areas that aren't protected by the walls are almost assuredly an easy way for colonists to get killed, your best course of action is to expand your base so it encompasses these resources. That not only means building walls but also building structures to make it easier to collect resources, houses to take care of civilians and troops, and a network of power towers to keep everything running.

To put it in StarCraft terms, most of your time will be spent fortifying and expanding your base while being vigilant of the eventual Zerg rush. The attack intervals are also random, and they don't come from a specific direction. You may build up one side well but need to scramble a few minutes later because the zombie hordes are coming in from a completely different direction. The penalty is rather steep, as any zombies that breach defenses have an almost guaranteed chance of infecting structures, and that can quickly infect others. Before you know it, a single breach can lead to the colony's downfall.

The rush of knowing that defeat can come easily is the game's hook. More than the steampunk aesthetic and the zombies, the knowledge that a simple mistake can wipe out all of your hard work is somewhat enticing, especially since the save files are wiped once you get a "game over" screen. No matter how bad the death is, you feel compelled to give it a few more hours, convinced that you finally have your strategy down. If anything, the fact that it captures the addictive magic so well this early on speaks volumes about the quality of the game design.

Even though the game is in Early Access, its lone mode feels fairly polished, except for the fact that pathfinding for your troops can break down at inopportune times. If the bugs were fixed and a few more maps were added to the Survival mode, this might be good enough. However, the developers have planned a few more modes for the final game. This includes a challenge mode where players play the same map in a competition for the longest survival time; it's something to take the place of an absent online cooperative mode. There's also a plan for a campaign that gives the player the backstory about why this is all happening in the first place, though there's no word on how long the campaign will be.

At the moment, They Are Billions is a game for strategy players who enjoy a high level of challenge. Even with just one mode to play through, there's enough to keep people coming back for more. With a few months to go before They Are Billions gets out of Early Access, it'll be interesting to see how the game progresses.