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

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 is distributed by DRM-free download. You'll also get a Steam key.

RimWorld is being created by Tynan Sylvester and Ludeon Studios. 9498 people pledged $268,132 on the RimWorld Kickstarter.

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.

A large, developed colony.
An well-developed colony at dawn. Click the image to zoom. Click here to zoom to the annotated version.

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.

Psychology

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 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.

Inspiration

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.

Lightning strikes during a rainstorm.
Lightning strikes during a rainstorm.
40,032+ sold

No PayPal account needed. You can buy with a credit card through Stripe.

Full Game Pack ($30)

Instant access to the latest alpha version as well as all updates up to the final game.

You'll also get a Steam key when the game is released on Steam.

Plus, get the Prototype Pack of five early game designs that eventually became RimWorld.

Name in Game Pack ($40)

Put a name (probably yours) into the game and appear as a pirate raider, colonist, traveler, or trader. Players will recruit, command, and fight you for all time! Includes the Full Game Pack.

Backstory in Game Pack ($125)

Like Name in Game, but you also get to write a unique character background, including backstories and skills.

Write yourself as an interplanetary detective, an entrepreneur, an ex-artist, or anything else you can think of! (Content must be fictionally coherent.)

Pirate King Pack ($200)

Like Backstory in Game, but your character will be a pirate leader who commands a group of raiders.

You can write a more intense, stronger character, and they'll play a key role. In “negotiations”, your character will be the pirate representative. Yarr!

Please note that player-created content must follow the creative rewards guidelines.





Tier upgrades

Want to upgrade to a higher tier? Just PayPal the price difference to [email protected] and email Tynan from your PayPal email with the transaction ID. I'll have you upgraded right quick!

© Ludeon Studios and Tynan Sylvester.
Memento mori.