RimWorld’s new horror expansion also happens to be its best (2024)

In RimWorld, you play as crash-landed survivors who have to eke out a new existence on a hostile planet, surviving and perhaps thriving between raider attacks, AI uprisings, and swarms of hostile insects. The game has a handful of expansions with new events, and the latest, Anomaly, is the scariest one yet. If you only have the spare scratch to pick up one RimWorld expansion, Anomaly is by far your best choice.

RimWorld is a game about rolling with the punches, which are doled out by the game’s storyteller, who manages the rate at which random events occur. For example, Phoebe Chillax trends toward the Stardew Valley side of the game, allowing the player to build farms, stockpile foods, and focus on the colonists’ day-to-day lives. Cassandra Classic, meanwhile, slowly ramps up the tension with escalating events, only pausing after particularly tough encounters.

A tough colonist might be able to fend off a raider attack only to get a deadly infection. I might stumble upon a temple full of riches only for it to be full of killer robots. A prison warden will get so mad over his girlfriend saying no to a proposal that he punches a turret until it explodes, killing him instantly. It’s this inevitable tragedy that makes RimWorld so compelling.

The game’s other expansions are Ideology, Royalty, and Biotech, each of which adds new ways to build up your colony and alter your colonists. Having to follow a set of religious tenets in Ideology makes for a fascinating social challenge, and I always have fun creating new genetic templates for my colonists in Biotech. But none of the expansions feel like they dramatically change the cadence of the game. I always just build up my base and wait for bots, bugs, or bullies to assault me. Once I win that battle, I put out all the fires (both physical and metaphorical) from the aftermath and build back up — rinse and repeat. It’s certainly fun, but on a long timeline, it makes the game feel a little stale.

Image: Ludeon Studios

Enter Anomaly, an expansion inspired by The Thing, The Cabin in the Woods, and other horror media. New settlements are always filled with ruins and resources, but now there’s a new feature: an ominous monolith. Attuning a colonist to the monolith triggers Anomaly events. This includes new enemies, of course, like stealthy shadow figures and giant slugs that can gobble down my poor settlers in one gulp. If I want to overcome these new challenges, I need to build containment fields, capture these baddies, and then study them for new technologies and rituals.

As anyone who has ever watched a single horror movie knows, this is a situation that’s absolutely ripe to go wrong. But there are tons of new, non-monster-related events that dramatically change the game and force me to play in a whole new way. I control the escalation of events by studying the monolith; the more I poke at it, the bigger a problem it becomes. This means I can’t get too overwhelmed by new events, and I have to take my time studying test subjects and preparing for the next step of escalation.

Take, for instance, the troubling instance of the golden cube. I got a call from a trusted ally asking me to take something off their hands. They’d even give me a whole bunch of extra supplies and military gear as a thank-you. Perhaps I should’ve been suspicious, but I’m a giver at heart, so I agreed. They sent a cargo pod, and inside was a fist-sized golden cube.

At first, everything was great. My villagers liked to look at it, and it put them in a good mood. I had my lead researcher take a gander at it, but she didn’t see anything alarming at first glance. But things quickly got complicated. My settlement’s cleric began to stop doing her regular duties in favor of wandering around and thinking absentmindedly about the cube. Then, she started building little cube statues from dirt and metal scrap. Finally, she stopped working on things altogether. Other colonists started to join her, and before long, you couldn’t walk a few steps in my settlement without tripping over a cube.

Image: Ludeon Studios

Afflicted colonists weren’t doing anything productive because they were too focused on the cube. They couldn’t leave the colony, either, or they’d get too upset about leaving the glorious cube behind. By the time my researcher realized there was a way to break the bond, a good chunk of my population was afflicted. Breaking the bond made them all go berserk, and a civil war broke out in my colony between the cube-afflicted and the cube-immune. I lost my cleric and a couple of other guys, but I made sure the funeral was nice.

You would think that’d be the end of my troubles, but shortly after, another faction offered me a nonspecific gift. This time it was a mysterious obelisk that duplicated my best miner, Paul. I now had two identical miners, both of whom claimed to be the real Paul. This seemed like a great resource, and I started harnessing the power to pump out a multitude of Pauls. But then I learned each clone would inevitably get organ failure. Luckily, RimWorld allows you to harvest organs from your enemies, and raiders still occasionally showed up at my base. So I managed to improvise a solution for Pauls’ various failing organs, and all it required was for me to set up a shady harvesting room.

This wild variety of events in Anomaly means that RimWorld feels much more fresh. The other expansions will affect what happens in your downtime, but the regular flow of combat and conflict feels the same. Anomaly adds so many weird and absurd events, and few of them can be boiled down to “a bunch of bad guys are running at your base.” These new forms of conflict can come from within, as a The Thing-style entity takes over your cultists’ bodies, or they can come from below, as a giant pit full of fleshbeasts opens up in the ground. Either way, I love these new and terrible stories that emerge from Anomaly, and it feels essential for shaking up a well-worn RimWorld experience.

RimWorld Anomaly was released on April 11 on Windows PC. The expansion was reviewed on Windows PC on a Steam Deck using a version bought by the writer. Vox Media has affiliate partnerships. These do not influence editorial content, though Vox Media may earn commissions for products purchased via affiliate links. You can find additional information about Polygon’s ethics policy here.