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A sci-fi colony sim driven by an intelligent AI storyteller. Read more

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This project was successfully funded on November 1, 2013.

A sci-fi colony sim driven by an intelligent AI storyteller.

About this project

• Get RimWorld at

• Follow @TynanSylvester

• Come chill at the Ludeon forums

• Stay updated at the Ludeon dev blog

• Chat with us at, channel: #rimworld

• Read the RimWorld Wiki

My last project before RimWorld was a game design book called Designing Games. If you're interested in the game design concepts and methods that I used to create RimWorld, check it out: Designing Games at

To everyone - thank you. To the backers, for backing the project. To the testers, for tirelessly hunting bugs. To everyone who helped build the community, chatted on the forums and IRC, and put content into the wiki. To Alistair Lindsay for making an awesome trailer soundtrack. To Rhopunzel for the title logo. To the YouTubers and streamers who spread the word. And to the people close to me for supporting me through months and months of failed prototypes. Without all of you this couldn't have happened. Thank you.

What follows is the original Kickstarter page. Since Kickstarter doesn't let anyone edit finished projects, this information will fall out of date over time. For the latest, go to


RimWorld follows three survivors from a crashed space liner as they build a colony on a frontier world at the rim of the galaxy.

For Windows, Mac, Linux. The game will be distributed by DRM-free download and backers will also get Steam keys. If you can't back here, there are PayPal buttons with the same rewards at

So far this has been a one-person project. I'm Kickstarting now so I can hire specialists to do music, sound, and art for the game.

The AI Storyteller

I've always thought the best part of games like Dwarf Fortress and The Sims was the stories that come out of them. That's why RimWorld is designed as a story generator. It's not about winning and losing - it's about the drama, tragedy, and comedy that goes on in your colony.

To keep things interesting, the game creates events like pirate raids, trader arrivals, and storms. But these events aren't random. RimWorld uses an AI Storyteller (modeled after the AI Director from Left 4 Dead) who analyzes your situation and decides which event she thinks will make the best story. There are several storytellers to choose from:

  • Cassandra Classic aims to create a rising curve of tension over the course of the game. Early on, the most dangerous thing she'll do is send a psychotic squirrel after you. Later on, bands of scavengers will arrive. In the late game, look forward to combined-arms attacks from mercenaries mixed with lightning storms and crop blights. If you want a traditional tension and difficulty curve, go with Cassandra.
  • Phoebe Friendly is for the player who just wants to build and watch a colony grow. She'll occasionally create minor disasters, but nothing that would threaten the existence of the colony. If you want a more relaxing game about growth and success, choose Phoebe.
  • Randy Random follows no rules. He may give you some amazing stroke of luck, like a trader selling an advanced weapon for a low price or a group of helpful immigrants, followed by a near-unbeatable pirate attack combined with an electrical fire. If you think losing is fun, you might want to try Randy.

And we're considering other AI Storytellers, too. High population storytellers, starvation storytellers, seasonal storytellers, moody storytellers, and anything the community thinks up are all on the table.

An aboveground colony at night.
An aboveground colony at night.

A motley crew

In RimWorld, your colonists are not professional settlers – they’re survivors from a crashed passenger liner. They'll be accountants, homemakers, journalists, cooks, nobles, urchins, and soldiers.

Each character has a background that affects how they play. A nobleman will be great at social skills (for recruiting prisoners or negotiating trade prices), but refuse to do physical work. A farm oaf knows how to grow food, but cannot do research. A nerdy scientist is great at research, but cannot do social tasks at all. A genetically-engineered assassin can do nothing but kill – but he does that very well.

You’ll acquire more colonists by taking in refugees, capturing people in combat and turning them to your side, buying them from slave traders, rescuing them, or taking in migrants.

Over the course of long games, players develop a motley group of refugees, pirate raiders, purchased slaves, and crashlanded survivors. The diversity of people makes each colony unique.

You won't get hundreds of colonists - we want to keep the number small enough that you can know each one individually.

Raiders burn out some walled-in colonists.
Raiders burn out some walled-in colonists.

The Tactics Engine

RimWorld uses an engine that I originally developed to power a tactical sim similar to Jagged Alliance 2. This means it has a lot of features designed to make small-team firefights interesting. For example:

  • There's a cover system that models low cover and leaning around corners.
  • There's a really nuanced algorithm for determining and reporting hit chances based on distance, skill, weapon, lighting, angle, and cover.
  • Weapons have some pretty deep stats.
  • The AI plans and executes tactical moves like flanking while trying to stay out of the enemy's line of fire. It uses a number of heuristic algorithms to analyze the battlefield and use the space effectively. It works with allies and avoids bunching up.

I think most base-builder developers wouldn't put this much effort into a tactics engine, but having inherited from that earlier project, RimWorld benefits greatly in unexpected ways.

Because of how important cover and positioning are in gunfights, our combat interacts deeply with the colony's layout and structure. This means players have to think about how they want to position their constructions to maximum advantage in future firefights. Combat in general is a lot more interesting than the traditional trading of blows you might expect in a base-building game. And it's possible to build a wide variety of base configurations for maximum tactical advantage against diverse foes.

Raiders assault from the north. The colonists have fallen back from their frontline sandbag positions. (click to expand).
Raiders assault from the north. The colonists have fallen back from their frontline sandbag positions. (click to expand).

The teaching system

This kind of game can be really hard to learn. So we've created an adaptive teaching system that watches your actions to figure out which parts of the game you understand, and teaches the parts you're missing. If you don't understand a control, the game will notice and help you out unobtrusively. If you already know something, the game won't interrupt you.

RimWorld also uses a notification system to make sure you don't miss anything that needs looking at. If you're low on food, or a colonist is about to go berserk, a message hovers in the corner of the screen informing you of the fact. No more getting annihilated because you missed some little detail. If you get annihilated, it'll be for a totally legitimate reason.


People in RimWorld constantly observe their situation and surroundings in order to decide how to feel at any given moment. They respond to hunger and fatigue, witnessing death, disrespectfully unburied corpses, being wounded, being left in darkness, getting packed into cramped environments, sleeping outside or in the same room as others, and many other situations. You can inspect a character's psychology at any time to see what they're feeling and why.

When a colonist becomes too stressed, they may suffer a "mental break". Some will give up and wander the colony for a time. Some will leave. And some will, in dwarfish fashion, become psychotic and throw a violent tantrum.

Sheckley the miner thinks about a recent battle while rescuing a wounded friend.
Sheckley the miner thinks about a recent battle while rescuing a wounded friend.

The universe

The flavor of RimWorld is a mix between hard sci-fi and the Old West. It's a rim world at the edge of the galaxy, far from the civilized core worlds. The planet is vast and mostly empty, and there are no strong civilizing authorities anywhere nearby. You're on your own.

The core idea in the RimWorld universe is diversity. In the this setting, humanity is spread across the galaxy, yet lacks any way of traveling or communicating faster than light. Combined with the fact that stellar civilizations regress (due to war or plague) as often as they progress, this means that someone traveling between stars may end up interacting with people at any level of development, from pre-agricultural tribes to transcendent machine gods.

Your starting colonists in RimWorld are at a technological level in the middle of this span. But you may end up interacting with people at much lower and higher levels, as well as acquiring and using their tools and weapons. In RimWorld, a single fight can involve a bow and arrow, a revolver, a charged-shot pulse rifle, and a near-magical teleportation device.

A developed underground colony with a large hydroponic grow-op.
A developed underground colony with a large hydroponic grow-op.

In its fiction, RimWorld draws a lot from Firefly. This is where it gets its subtle Western vibe - frontier living, an arid environment, sparse law enforcement, and the constant threat of outlaws. We're also heavily inspired by science fiction novels like Dune and Alastair Reynolds' Revelation Space series (which both Alistair Lindsay and I are huge fans of). The Warhammer 40,000 universe also forms part of our inspiration.

In terms of game design, the game draws most from the 800-pound gorilla of the simulation genre, Dwarf Fortress. We also take ideas from indie hits like FTL (our semi-random event format) and Prison Architect (its way of presenting a complex world in a comprehensible, interactive way). And, there are many others.

We're in the gaming press!

RockPaperShotgun: (Space) Colonial Ambition (September 18)

• The Jace Hall Show: Former Bioshock Infinite Developer Goes Indie With Space Colonization Sim: RIMWORLD (September 18)

• BeefJack: Dwarf Fortress in Space: RimWorld (September 19)

RockPaperShotgun: Outer Limits: RimWorld Lands On Kickstarter (October 4)

WorthPlaying: RimWorld announced, seeks crowd funding (October 4)

RimWorld's development is arranged into "modules". The plan is to work until one module is finished, release it, and then choose the next based on what people want. This way, the game will grow organically according to the feedback of the community, while remaining playable at all times.

As a Kickstarter backer, you'll be one of the voices with the most influence over which direction we take the game. Perhaps you'll like some of the modules I'm interested in below. And if you've got an idea for another, please let us know.

Note that this list of modules isn't a roadmap or a plan. These may not all ever be finished. They're options I'm offering to the community. Which way should we take the game after the Kickstarter?

Proposed Modules

Tynan Sylvester - Design and programming

I've been making games over ten years. The first were Unreal Tournament mods, followed by my four years at Irrational Games working on BioShock Infinite, followed by the indie projects I've worked on since. I also wrote a game design book called Designing Games and published it with O'Reilly Media. There's more about me at my website, including various articles I've written on game design.

Alistair Lindsay - Audio hero

Alistair is perfect for this project. He did audio on games like DEFCON (haunting!), Darwinina (quirky!), and Prison Architect (engaging!), so he knows how to work with this kind of game and he knows how to handle an indie sound project top to bottom. He's been working game audio since 1999 when he started with Rare. 

Alistair doesn't just try to make an effect in a game sound like what it represents. He thinks about how his audio will make players feel on a subliminal level. He's going to be doing magic like adjusting ambience, interface, and game sounds to match the AI Storyteller's desired mood, to make you feel tense or relaxed or excited just as he wishes. I'm almost scared of him.

The dude is legit and I'm really happy to have connected with him. As a first sample, Alistair was good enough to do the audio for the RimWorld trailer. I think he did an awesome job of nailing the sci-fi/Western feel.

To Be Determined - Art

We're still in talks with some artists who are ready to help develop a unique and effective look for the game.

Is there more info?

Yes. See our development blog, and the forums, where testers have been discussing their play experiences. To keep updated, you can also follow me on Twitter.

Why Kickstarter?

The game is getting to the point where I (Tynan Sylvester) can't do everything it needs myself. It needs audio, and it needs art. This means I need to contract people to do these things, which takes money.

In addition, there are basic costs to setting up a corporation, software licenses (e.g. Unity costs $1500), and so on.

It looks a lot like Prison Architect. What's up with that?

Blame my (Tynan's) lack of art skill - especially with characters. I made the character art you see in the trailer as a stopgap, and borrowed the Prison Architect style because I'm not a good enough artist to develop a new one. They were never intended to be final. With this Kickstarter, we'll be able to get a real artist who can sit down and develop an original style for RimWorld.

I've talked with the original Prison Architect artist, Ryan Sumo, and he's fully supportive of RimWorld. We didn't share any art or code with the PA guys.

When will the game be available?

The game works now. If you're in the influencer tier, you'll get access to the current pre-alpha as soon as the Kickstarter ends and we work out the payment and download details (which could take a few days after November 1).

I've run several playtests and verified that real people can pick it up and enjoy it. It is, however, a bit light on content, and there are bugs. I'd like to squash this stuff as fast as possible.

I think we can have the first more stable and well-rounded public alpha (with audio and art contributions) out in January 2014.

When will it be completely done?

After the public alpha in January 2014, I'll continue development based on what people seem to want. I don't know how long after that the game is finished. Development could continue for a long time, depending on community response. This is really the kind of game that could expand forever. Regardless, everyone who gets the alpha will continue to get updates right up to the final game.


Nope. No DRM.


RimWorld is currently being tested on Windows and Mac. Unity (the technological base for the game) also supports Linux, so we'll be releasing for that too. There may eventually be an iPad version, depending on how the Kickstarter does, but this isn't planned in the next few months.

How do we know this isn't vaporware?

You should be concerned. Kickstarter projects often don't get finished. But this one will be. Here's how you know:

  • The game already exists, and the testers are already having good experiences with it. We've got a small crew of testers on the Ludeon forums sharing their experiences with the game. Take it from them, not from me.
  • I have a history of finishing projects. I wrote a book and got it published with O'Reilly media. I'm a professional with experience at a major studio. I know how to schedule a project and handle design risk.

I wasn't willing to make this project public until I knew it was on the path to being a real game. That's why I made so many prototypes before settling on this concept. Most game ideas don't work well. But this one does.

There are still risks in this project, but they are about individual features, not the project as a whole. Some ideas will fail, and some parts will need to be redesigned. But RimWorld will not become vaporware. We've already got a game here, and it's a good one - we just need your help to make it as great as it can be.

Are there multiple Z-levels?

No. RimWorld isn't really about digging the way Dwarf Fortress is, and there are tons of interesting story things you can do with no Z-levels. We're focusing on the story-generating parts of the game. Z-levels may come eventually, but not soon.

Will there be multiplayer?

It's possible; and if the community asks for it consistently I'll gladly put it in. But it's not immediately on the to-do list and it would be a significant amount of effort to do. For the near future, I want to work a lot more on fleshing out the library of events and the AI Storytellers.

Is there a community?

Yes! There's tons of good discussion on the Ludeon Forums. You're invited to contribute your ideas as well. Fans have even created a RimWorld subreddit. I maintain a development blog at the Ludeon Studios website.

For the creative rewards, what are the constraints?

To keep things consistent, there's a whole set of documents about this. Please check the creative rewards guidelines.

Can I make YouTube videos/interview you/try the game for press purposes?

Probably. If you're a journalist or a YouTuber who gets at least 1000 views per video, please email me.

Lightning strikes during a rainstorm.
Lightning strikes during a rainstorm.

Risks and challenges

See the FAQ above: How do we know this isn't vaporware?

Learn about accountability on Kickstarter


Have a question? If the info above doesn't help, you can ask the project creator directly.

Ask a question


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    Author - I'll work with you to create a new story event that can happen to colonies. This could be a new sort of weather, a different style of raid, or a trader offering a strange bargain. Or, whatever else you can think of! Must be within feasibility and fiction constraints (message me if not sure). Includes all other tiers Mercenary and below.

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Funding period

- (30 days)