Design Analysis: RimWorld

Tired, hot, and in mental anguish, fifteen colonists sprint through the forest in the dead of night. They reach their destination, an outpost, armed with assault rifles. The haggard group lines up, bracing for the conflict ahead. Their home, overrun with monstrous insects that burrowed in from underground. Looming in the clearing, a psychic ship, a mental weapon, emanates whispers and thoughts that infect the minds of men and women. Among the band is a man named Zeiph who prepares for a grim task. He cannot fight, it is not in his nature, but he has a key role in the rescue of this colony. Once the ship is disturbed, its defenses will kick in by sending out mechanoids to attack all who are nearby. Zeiph will dash through the chaos of the imminent fight, and retrieve from the ship its AI persona core. This core was the last piece of the puzzle, the last thing that is needed for their functioning ship, and this was the only way to get it. Their one means of escape.

One of the colonists begins the assault, firing at the ship with their assault rifle. Immediately, about a dozen mechanoids spring from the ship and open fire on the colonists. The colonists focus fire on the ship, attempting to breach its hull. The shell of the ship breaks and falls apart, much like the front line of the colonists. Zeiph leaps into the fray, running towards the ships exposed core. The mechanoids turn to him and open fire, tearing through his personal shield. He falls to the ground unable to move due to his injuries. In a panic, the rest of the colonist make a mad dash for the persona core. None of them make it. The remaining mechanoids, turn on the colony and begin to burn it to the ground. Zeiph, the first one down, is the last to die, alone and in a pool of his own blood. As the world darkens around him he thinks back on his life in the colony. He recollects on the marriages, fights, and clan wars. He recollects the goals of his friends and how they will go unrealized. He closes his eyes and releases his grasp on the world. This was the end of one of my most successful colonies.


RimWorld is a base building management simulator made by independent developer Tynan Sylvester. Originally released in the fall of 2013, it has slowly grown into one of the more popular games on steam (looking at Steam’s “top games by current player count” chart right now, it’s hovering around 50). A base building management sim is a type of game where the player has no direct control over the environment but commands non-player character (NPC) units to carry out tasks.

Before we start analyzing the game, we should take a look at its development history. Tynan released the first version of the game in 2013 and has continually released new versions of the game since then. Each iteration adds more mechanics to the game, based on his own goals and suggestions from the player base. RimWorld is constantly evolving and is formed from a collaboration of the developer and the game’s audience.

RimWorld was a game made with mods in mind. The core of this game serves as a framework for future add-ons. This has fostered a community that creates mod packs which can change the experience dramatically. For example, there are a group of mods themed around the Cthulhu mythos, creating scenarios with eldritch abominations and horrific sanity-bending events. Another mod pack turns off all advanced technology and forces all factions to use medieval style weapons. The modding community has added an enormous range of variability, which has resulted in a game that can be custom tailored to any players needs.


RimWorld takes place on a randomly generated planet on the outer parts of a solar system (A world on the rim, RimWorld. get it?). There are many different factions and settlements that dot the land. Each settlement has their own people with different levels of technology and attitude toward the player’s faction. The players slowly build a group from wanderers, slaves, and recruited prisoners.


A marriage ceremony next to the potato fields. How romantic!

As far as flavor goes, this is it. RimWorld still remains compelling despite this bare bones framework by using emergent gameplay. This means that the game was not meant to have a story itself, but the events and mechanics of the game allow the player to form their own narrative. Colonists have feelings, desires, friends and enemies. Although it’s not perfect, each unit acts like a human. The story mentioned in the beginning, that narrates the end of my colony, is an example of how emergent gameplay can occur. Although parts were embellished for dramatic purposes, everything in the story happened due to the mechanics of the game. Ask another RimWorld aficionado and you’ll get a different story, possibly one with a happier outcome.

To quote Tynan;

“RimWorld is not designed as a competitive strategy game, but 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.”


RimWorld is not about one specific colony or faction. When a new game is started, RimWorld will generate a new planet, with new factions, Players can put as much work into one colony as they want, and are able to start a new one for whatever reason. For the mechanics portion of this article, we will go through the creation process of a session, which is where the rules are determined.

When you begin a new game of RimWorld you are prompted to pick a scenario. This will determine what items the player will start with, as well as additional rules to implement during the player’s games. These rules are a marvelous way keep players coming back. New games happen frequently in RimWorld, which can lead to players finding the optimal strategy to a stable colony. If this becomes too routine for the player liking then they can choose to start with one colonist, or with fewer starting items. There are three base scenarios. The first one, entitled Crashland, was the only scenario available in earlier releases of the game. scenario-1scenario-2

The three scenarios presented are not the only modes available to the player. They also have the option to custom tailor new scenarios. With the scenario editor, players can tweak aspects of the game to give their new colony a boost, or a handicap. Not only can you determine what items your colony will start with, you can change the rules of your game. Maybe you want all your colonists to be cannibals. Maybe you want to increase the global walk speed of your colonists so everyone runs lightning fast. Maybe you want the weather to be a permanent nuclear winter. Players can tweak almost every aspect of the game, allowing for a wide range of play-styles. You don’t want to fight and rather focus on other aspects, like colony efficiency? Turn off enemy raids. You want the walls of your base to be splattered with the blood of your enemies? Make a raid happen every week. There’s even a random scenario generator if your feeling lucky. Giving the players an opportunity to fine tune their experience is good for replayability, as the player can expect new challenges to arise in their new colony.

Next, you will be asked to choose an AI storyteller. This is an artificial intelligence (AI) that will pick events to happen to the colony. Depending on the AI storyteller chosen, it will select events that it feels would be best for the story. Storyteller.pngThe challenges of this game come from the storyteller throwing curve-balls at you. Testing the player on their preparedness and their ability to think on their feet. Let’s say the power goes out and at the same time an enemy raiding party decides to show up at your front door. Do you have a set of doors and thick walls to keep enemies out until power returns so your turrets can rip through the invaders?

The third step is choosing where you want your colony to land. Players will be shown a procedurally generated planet, dotted with NPC factions. Players can choose how much of the planet to render. The influence of the player’s colony rarely stretches further than 30%. If they want to save on processing, they can choose to ignore the other 70% of the planet. The surface is made up of hexagons each with their own biome and elevation. These can range anywhere from a hilly boreal forest, to a mountainous desert, to an ice sheet. The climate has a big impact on what your colonists needs. Climates with extreme weather will require rooms with controlled temperatures and different clothing. There are also factions that must be taken into consideration. A location may have everything you desire, but is close to a pirate encampment, and is more subject to raids.

The final step before the game begins is generating your colonists, sometimes called “pawns”.  You may hit the randomize button as much as you want, and it will generate a new colonist. It’s at this point where we need to take a slight detour to talk about the most important mechanic in the game; the Colonists. Colonists are people, they have a set of skills, a backstory, and traits. The backstories are chosen at random from a list and the skills are chosen semi-randomly based off of the player’s background. Skills are what your player is able to do and their score is a representation of how good they are at that skill. It is also possible for your colonist to have a passion for certain skills. This increases the amount of experience they get when doing the task, making it easier to increase the level of that skill.


DISCLAMER: The characters facial features, as well as the trait codependent and the skill managing are not native to the game. These were added by installing a mod.

But one of the most defining features of the colonists are their traits. These will add depth to your character and provide a give and take for players to consider. For example, a colonist could come up with a really good set of skills, but have a concerning trait like pyromaniac. The colonist may be useful when they’re mentally stable, but if they get in a foul mood they could light a fire in the base.

After you assemble your motley crew of space explorers, you’re ready to touch down and start playing. It was stated earlier that the main focus of the game was to tell stories. world5There are, however, win conditions to strive toward for the players who want to have a conclusion or a goal for their colony. One such goal is to build a ship and leave the planet. To do that you would need one or more of your colonists to research new technology. This will take some time, and will require a safe place to do it. Along with safety, your colonist will need food and shelter from the elements.

This is the focus of the game, to command colonists to provide for themselves and each other. The player needs to consider the peoples’ needs and designate the priority of tasks. The way the colonists know what task is appropriate for them is by referring to the work priority table. On this table, tasks are laid out left to right for each colonist, who are organized top to bottom. The player clicks on a square associated with a task which adds or subtracts from a number. This number is the priority of the job and is on a scale of 1 to 4, with 1 being a high priority and 4 being low. The colonist could also have a 0 in a job, meaning that the colonist will not do that task at all. Tasks on the left are a higher priority than the task on the right. The colonist checks its work priority to see if any priority 1 tasks are available. If there is a job available it will go do it. Otherwise, they check if there are any 2 priority jobs, then 3, then 4.


Screenshot provided by This is an earlier version of the game and doesn’t show bedrest or handling.

There are 21 skills in the game currently;

  1. Firefighting; The colonist’s ability to put out fires, they will only put out fires within their home zone. This job doesn’t pop up that much, but when it does you want it done… NOW. This should be on a high priority.
  2. Patient; The colonist’s ability to go to a bed to receive treatments like surgery.
  3. Doctoring; The colonist’s ability to treat other colonist’s injury or illness.
  4. Bedrest; The colonist’s ability to rest in bed until well. This should be a high priority, as working when ill can have ramifications.
  5. Flick; The colonist’s ability to turn on and off electric devices. This task is a lot like firefighting, as in the job doesn’t come up that often, but when it does you want it done quick.
  6. Warden; The colonist’s ability to deal with prisoners. These tasks include feeding, changing locations, and recruiting if applicable.
  7. Handle; The colonist’s ability to tame animals, as well as feed, train, milk, shear, or slaughter already tamed animals.
  8. Cook; The colonist’s ability to cook food. Your going to want someone with at least a 5 to avoid food poisoning.
  9. Hunt; The colonist’s ability to hunt wild animals.
  10. Construct; The colonist’s ability to make objects like walls, turrets, beds, etc.
  11. Repair; The colonist’s ability to repair structures that are damaged within the home area. It’s worth noting that this does not provide the ability to repair objects like weapons or clothing. This is focused on repairing structures like walls and workbenches.
  12. Grow; The colonist’s ability to plant and harvest crops. Some plants require a higher skill to plant, like healroot.
  13. Mine; The colonist’s ability to remove naturally occurring rock obstacles.
  14. Plant cut; The colonist’s ability to chop down trees and clear shrubs.
  15. Smith; The colonist’s ability to create weapons .
  16. Tailor; The colonist’s ability to make clothing from cloth or leather.
  17. Art; The colonist’s ability to make sculptures, a very useful skill later to get some cash.
  18. Craft; The colonist’s ability to make objects like stone blocks or bionic arms. Smithing, tailoring, and crafting all use the Same skill, “crafting.”
  19. Haul; The colonist’s ability to carry items to their appropriate locations.
  20. Clean; The colonist’s ability to clear areas of dirt, blood, vomit, etc.
  21. Research; The colonist’s ability to study new technology.

The player is in control of this job chart, as well as most aspects of the colonist’s lives. The player can control what the colonist wears, their sleeping schedule, drug use, their working schedule, and more.

During the game, events will happen to the player at semi-random intervals, determined by the AI storyteller. These events range from mad animals attacking nearby colonists to cargo pods falling from the sky that provide useful items to the colonists. The events act as obstacles in the player’s way and can even lead to the downfall of the base itself. Having these events forces the player to think about the future and allocate resources to deal with potential threats. Being too complacent with your defenses could lead to insufficient firepower, and a raiding party could take over your base further on in your game.


A poison ship crash lands at the colonists front door. They’ll need to take care of it before all their crops are destroyed by the poisoned ground.

Not providing for colonists also has its consequences. There’s the obvious penalty for not feeding colonists which is starvation. There are some needs, however, that are not so obvious, which can slowly accumulate over time. When something happens to a colonist, they get what’s called a “moodlet”. These moodlets can give a positive or negative effect depending on the source of the moodlet. Colonists will get stressed out by seeing a dead body for example, that gives them a negative moodlet. Too many negative moodlets will decrease the mood of a colonist until they break mentally.

Mental breaks are the consequence for not providing adequate living conditions for a colonist and each colonist has a different break threshold. These devastating ramifications, or be completely benign. One colonist might hide away in their room and not work for a couple days. Others can go berserk and start fights with nearby colonists, hurting or even killing them. Mental breaks can mostly be avoided with careful planning, but there will often be times where you simply cannot provide something for your colonist. In that case, try to make their life easier in another aspect. High-quality meals are a sure fire way to improve the mood of your colonists, though you’ll need someone with a high cooking skill.

RimWorld is a game about surviving, efficiency, and teamwork. A game that uses its mechanics to craft stories. RimWorld allows for its players to set their own goals and determine how difficult their climb is. The randomness, coupled with the simple to pick up controls and depth of mechanics, form a game that can be played time and time again, each with their own story.