Video games don’t make for easy translations to RPGs, especially if the video game isn’t really an RPG itself. For this continuing System Hack I’m aiming to put together a tabletop RPG that plays like a Colony Sim, and hopefully using Cortex Prime to do it. Before we get into any rules design, though, it’s time to look at my core inspiration for taking this project on in the first place.

RimWorld is a colony sim video game designed by Tynan Sylvester, and now supported and expanded through an entire team at Sylvester’s studio Ludeon Studios. The game was released in 2018 but had been in Early Access for five years at that point, and it continues to see frequent updates and support, including several large DLCs.

So how do we take that concept and translate it into a TTRPG? It’s not about the exact setting of RimWorld, though certain hard sci-fi conceits are going to port over. It’s more about understanding what experience the game produces, and then figuring out which elements of that experience could be employed to good effect in a tabletop game. With that in mind, let’s take a look at RimWorld’s premise and its mechanics, and get in the mood for some reverse engineering.

Premise and Setting

The premise of RimWorld is rather straightforward, but both the setting and mechanics are revealed to have much more complexity than they initially let on. A default start of RimWorld puts you in control of three colonists who have crash landed on a planet with a modicum of supplies and a pet. Your goal, insofar as there is a singular goal in the game, is to build a spaceship that lets you leave the planet. Even if you were playing the game focused on building that spaceship to the exclusion of all else, you’d still need to gather a lot of resources and research a lot of technology in the game’s tech tree to get there. Further complicating this is that over the several in-game years it will take to build that ship, you have to keep your colonists alive and productive. This means growing, hunting, or foraging food, building shelter, making clothes, and keeping colonists mentally stable, be that through recreation and social fulfillment or drugs and mind control implants. It also means defending your colonists from raiders, hostile animals, and, eventually, horrifying mechanoids from the planet’s past.

As you progress through the game and encounter more groups of people on your RimWorld, you start to get more of an idea for the setting. RimWorld is a somewhat ‘hard’ sci-fi setting, where faster-than-light travel does not exist. Instead, the setting’s space colonization is enabled by two fictional technology conceits. ‘Cryptosleep’ is a form of suspended animation that allows a being to be woken up hundreds or even thousands of years later without any deterioration. Additionally, the ‘Johnson-Tanaka Drive’ is a space travel technology which, while not faster-than-light, is equally fanciful because it is reactionless, requiring no fuel mass to accelerate. These two technologies taken together lead to a world where humanity is spreading out throughout the galaxy…very slowly. Over more than three millennia, humans have made it about 1200 light years from Earth, and experienced immense cultural and technological drift. Closer to Earth, to the start point, technology has evolved to the point of superintelligent AI, designer genetics, impossible nanotech, and other wonders. Once you get out further, though, to the ‘Rim’, human technology may be literally neolithic, with fire and bronze representing the apex.

Another fascinating worldbuilding quirk in RimWorld is that the setting supposes almost no alien life. While some animals, namely the Thrumbo, are implied to have been alien, the vast majority are Earth fauna which have been seeded and in some cases genetically modified for their terraforming role. This means in the game most plants and animals are familiar or at least have a familiar touchstone; it also provides a justification (and disturbing backstory) for the more exotic animals like Boomalopes (antelopes which secrete flammable liquid that can be used as fuel). Even with humans being the instigators of most if not all life on these planets, genetic drift in both human and non-human populations allows for a wide range of animals, from the mundane to the terrifying. Of course, thanks to the Biotech DLC, inducing even more genetic drift is added to the game’s mechanics, among many, many other things.

Mechanics

At its core, RimWorld is a life sim, constantly monitoring the interactions between human pawns, non-human pawns, and the environment. The environment has a temperature, time of day and year, and weather, and these elements affect things happening within the game environment, including plant growth, fires starting and being put out, corpses rotting, and other events occurring in the background. One key environmental status is the split between ‘inside’ and ‘outside’, which begins to differentiate the built area that your colonists create. The simulation isn’t meant to be overcomplicated; unlike Dwarf Fortress the map is two dimensional with no z-layers. At the same time, there are some very interesting simulation tidbits, like heat transfer and (more annoyingly) dirt transfer. It all provides for some neat background, but the pawns are where things get even more sophisticated.

All animals and humans are pawns, and though the humans are a bit more detailed and more advanced, a lot of the mechanics work the same way. All pawns have limbs and certain organs, which feed into the detailed health and combat systems. All pawns can be butchered for leather and meat, which is what enables the game’s rather infamous cannibalism (and human leather hats). While healthcare (or slaughter) of pawns is handled fairly consistently, humans have much more detail around who they are as people (or as characters), and that detail will feed right into the aspects of RimWorld that could make for an interesting RPG.

In the simulation, characters are made up of skills, traits, and thoughts. Skills and traits are the ‘sticky’ character elements, while thoughts are based on events and environment. Traits are the ‘inherent’ elements, forming core restrictions of the character’s personality and capabilities. Traits include ‘greedy’, ‘fast learner’, ‘lazy’, and of course the infamous ‘pyromaniac’, among others. Typically traits either modify behavior, modify physical attributes (which in the game are things like walk speed and working speed), or modify skills, either buffing or debuffing their effectiveness or learning speed or even gating them off entirely. Skills are most equivalent to their counterpart in a tabletop game; RimWorld has 12 skills which govern most of what characters do in the game, including Shooting, Medical, Construction, and Animals. Skills in the game progress based on use, though the rate of progression is affected by traits and the environment.

Thoughts add up to give the character’s Mood, driving the Sims-like element of the game. They vary from environmental reactions that only affect the mood within a given room (too hot or too cold), buffs/debuffs from events that occur (ranging from parties to funerals to breakups), all the way to persist inherent states (pain, hunger, drug effects). The way that thoughts affect character behavior is relatively simplistic, with high mood characters more likely to earn ‘inspirations’ that give them guaranteed good outcomes on certain tasks. Low mood characters are more likely to suffer a mental break, which results in the character refusing to do any work as they, among other things, wander around in sadness, lock themselves in their room, attack someone, or binge on drugs or food.

To keep your characters productive you generally have to keep them happy, and that means providing them with positive Thoughts throughout their day. Part of this is keeping them fed and clothed (with nicer clothes and food having additional benefits), another part keeping them sheltered and at a comfortable temperature (and here you’ll quickly find that it’s not enough for the room to be appropriately cool or warm, it also needs to be clean and attractive), and finally keeping their social health in check. This means having friends and lovers, but also not being in too close proximity with any enemies (though if one of your characters’ enemies dies, they’ll get a little mood buff). All of these things come together in different ways to provide many, many different ways to run an effective colony, but all the happiness in the world can’t help you if you’re attacked by raiders or, worse, a gang of rabid alpacas.

The game’s encounter system is based on a ‘storyteller’ who doles out events depending on how they’re programmed. ‘Cassandra Classic’ controls random events with consistent and steadily increasing difficulty, ‘Phoebe Chillax’ tones down the outside events so you can focus on your colony, and then there’s Randy. ‘Randy Random’ not only throws all logical sense to the wind, he throws in some truly, well, random events both on the negative and positive ends of the spectrum. Playing with Randy as your storyteller is much more likely to generate the gang of rabid alpacas, but you could also have cargo pods full of goat milk fall from the sky. I find I most enjoy playing with ‘Randy Random’ both because the random events make the game more interesting, but also because the difficulty level of exogenous events isn’t really driven by the storyteller alone. Each storyteller is sending events based on recent events (both the events sent by the storyteller as well as if a colonist has recently died or been wounded) as well as the colony’s possessions, measured in both wealth and number of pawns (both human and animal). This means that no matter which storyteller you pick, the better your colony does, the more intense the events will be.

As your colony progresses and your characters study their way down the tech tree, they’ll unlock more and more advanced technologies until you start unlocking the starship parts which trigger the endgame. Although better tech tends to make for happier and more productive colonists, it also ramps up the challenge in a couple of ways. Resource gathering will always be a key part of your colony’s “do-loop”, but you’re going to quickly find yourself moving from chopping wood and mining surface deposits of steel to looking for exotic ‘plasteel’ and uranium deposits and using ground-penetrating radar to find mineral deposits to drill for. At the same time, both these exotic materials and the tools you use to extract them are worth more in-game currency, driving up your colony’s wealth, and making the combat encounters more and more difficult. You can make more and better weapons, too, but those are also worth more money, further upping your wealth, pushing the need for ever more weapons…since you can’t actually escape the upward spiral, colony design and strategy ends up being the key element which helps you persist even in the face of greater and greater dangers. And no matter how good you do, the wrong freak event could send it all up in flames. Raider attacks, sure, but also fires, electrical faults, and even prison breaks (did I mention you can take your attackers prisoner? You can take your attackers prisoner) can spell a sudden end for even a well-planned colony. It sometimes seems very unfair (though maybe that’s because I always play with Randy Random), but that’s just another day on the Rim.

RimWorld takes a simple idea but executes it in a complex way, and that’s one reason the game has been so popular. There’s also been more and more added to the game through its DLCs, including a system of ideologies, more backstory around a feudal society that exists in your star system, biotech enhancements, and even options for just a straight-up horror version of the game. The most recent DLC, Odyssey, came out last week and expands the game’s travel options. Previously, you could send a caravan of your colonists to other points of interest on the map, whether that’s to find a ruin, raid a nearby settlement, or even just go trade. One of the big things Odyssey adds is a late-game gravship, which allows you to explore the world more quickly and even reach objects in orbit. This expanded late-game content makes it even more satisfying to see your colonists through from a pile of supplies and scrap metal to a spaceship that, thanks to the DLC, you can now control.

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Laying out the basics of RimWorld also illustrates how a tabletop RPG colony sim would have to differ from a video game. I’m not going to be employing a real-time simulation of environments, moods, and random events. Instead, the game should provide the key elements of interactivity and reactivity that we’d want to make a colony sim compelling. This likely means spending less time on things like exact temperature or limb-by-limb healing rates, but going into more detail about the characters, what their stories are, and why they want to get off the planet (or not!). RimWorld has a bunch of very interesting details to let a player make some of these stories in their head, but in a TTRPG context I think we need to strike a different balance between the day-to-day workings of the colony, the broader events happening all over the planet, and the inner lives of the colonists and the stories that those can create.

We’re not quite done with RimWorld in this System Hack. Next time, we’re going to build up our conceit, using RimWorld as a guide. There are some really interesting ideas in the game’s worldbuilding, and while I’m not interested in copying them, per se, I think that there’s something really neat about the core setting concept of human colonization of the galaxy using slower-than-light travel (and all the cultural stratification that causes). Using that idea, and playing around a bit more with the worldbuilding, the next step will be to figure out what our game will actually do, and then laying the groundwork for how best to realize that vision. It’s a pretty big canvas, but I’m excited to see what it all looks like in the end. There’s still a lot of blank space to work with, but that can be quite a good thing for a System Hack.

RimWorld and its expansions are available on Steam.

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