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Events are random occurrences that can strike a colony at any moment. They range from everyday occurrences like passers by, to all out assaults on the colony.

The player will be notified of an event's occurrence by an envelope icon that will appear down the right side of the screen. Envelopes are color coded according to whether the event is good or bad - blue envelopes denote good events, red envelopes denote bad events, and yellow envelopes denote neutral events.

Clicking an envelope will open up the message with a description of the event, and the option to either dismiss the notification or, where possible, go to the location of the event. Alternatively, notification messages can be dismissed without opening via right click.

Event Data

Category Name Common Name Chance Favorability Min Time Before
Repeat (days)
Disease Flu Flu varies by biome Bad varies by biome
Disease Plague Plague varies by biome Bad varies by biome
Disease Malaria Malaria varies by biome Bad varies by biome
Disease SleepingSickness Sleeping Sickness varies by biome Bad varies by biome
Big Threat RaidEnemy Raid 9.0 Bad 0
Big Threat AnimalInsanity Mad Animals!: (Animal name) 1.0 VeryBad 1
Big Threat ShipPartCrash Psychic Ship 1.5 Bad 30
Big Threat ManhunterPack Manhunter Pack 2.0 Bad 15
Big Threat Infestation Infestation 2.8 Bad 20
Special RaidFriendly Friendlies 3 Good 0
Special AgentRevealed Traitor 1.3 VeryBad 40
Small Threat AnimalInsanitySingle Mad Animal 5 Bad 3
Small Threat ColdSnap Cold Snap 3 Bad 30
Small Threat HeatWave Heat Wave 3 Bad 30
General Bad Beavers Beavers! 1 Bad 15
General Bad Eclipse Eclipse 3 Bad 30
General Bad SolarFlare Solar Flare 1.5 Bad 30
General Bad PsychicDrone Psychic Drone 1 Bad 30
General Bad ShortCircuit Zzzt... 1.2 Bad 15
General Bad CropBlight Blight 2.5 Bad 8
General Bad ToxicFallout Toxic Fallout 0.25 Bad 180
General Bad VolcanicWinter Volcanic Winter 0.11 Bad 280
General Good TraderArrivalGeneral (Trader type) 13 Good 0
General Good TraderArrivalSlaver Pirate Merchant 4.5 Good 0
General Good TravelerGroup Travelers 8 Good 0
General Good VisitorGroup Visitor(s) 8 Good 0
General Good WandererJoin Wanderer Join 0.4 VeryGood 0
General Good ResourcePodCrash Cargo Pods 6.0 Good 0
General Good RefugeePodCrash Escape Pod 1.5 Good 0
General Good PsychicSoothe Psychic Soothe 1.0 Good 30
Neutral RefugeeChased Refugee Chased 2.5 Neutral 15

Weight of each disease per biome
Biome Name Flu Plague Malaria Sleeping
Arid Shrubland 100 100 0 0 30 30 60 60
Desert 100 100 0 0 30 30 60 60
Extreme Desert 100 80 0 0 30 30 40 40
Boreal Forest 100 100 0 0 30 30 50 50
Tundra 100 80 0 0 40 40 30 30
Ice Sheet 100 80 0 0 30 30 0 0
Tropical Rainforest 100 100 160 140 30 30 80 80

Mean time per disease by biome (in days)
Biome Name Mean Time
Between Diseases
Flu Plague Malaria Sleeping
Arid Shrubland 60 228 228 0 0 760 760 380 380
Desert 80 304 304 0 0 1013.33 1013.33 506.67 506.67
Extreme Desert 90 288 360 0 0 960 960 720 720
Boreal Forest 50 180 180 0 0 600 600 360 360
Tundra 80 256 320 0 0 640 640 853.33 853.33
Ice Sheet 90 37.5 30 0 0 11.25 11.25 0 0
Tropical Rainforest 30 216 216 135 154.29 720 720 270 270

Event Descriptions

Big Threats

Enemy Attack

Commonly known as a raid, this event comes in several types. The size of a raid is determined by your colony's wealth, and the difficulty setting of the AI Storyteller. It is possible for multiple raids to occur at the same time, possibly to the benefit of the player if both raids are from opposing factions.

Different types of raids include:


Siege raids typically have a party of raiders arrive and set up a small camp along the edge of the map with a number of sandbag walls and mortars which could be High Explosive (HE) or Incendiary. They will fire upon colonists, colony structures and any visitors or other raiders from factions they are hostile to, only stopping to eat and sleep.

Siege parties will abandon their camp and any remaining construction to assault the colony when they either run out of artillery shells, all of their siege weapons are destroyed or they suffer significant casualties. Any remaining supplies and objects from their camp and be claimed, deconstructed and used by the player.


Assault raids arrive either via the edge of the map or by drop pod. They may assault the colony immediately, or stage for a time before launching their attack, allowing colonists time to take up defensive positions, or to skirmish/counter assault the attackers.

Mid-Base Assaults

A group of raiders arrives via drop pods directly in the player's base, leaving little time to prepare. Drop pods may punch through a constructed roof or thin rock roof.

Psychic Wave

A psychic wave is a pulse of psychic energy that immediately drives a number of the local wildlife insane, causing them to attack the nearest human, and any animal that happens to be standing in their way. A psychic wave is not to be laughed at - most of the wildlife in RimWorld is quite fast, and can close the gap to a colonist before they can get off a second shot, often leading to the colonist being overwhelmed.

Ancient Ship Crash

This event sees a massive piece of an ancient ship crash down to the surface near (or even in) the colony. This ship part happens to contain a hostile AI core that emits a psychic drone that negatively affects the mood of all humans on the map. This drone begins low, but grows progressively stronger the longer the ship part remains, therefore it is advisable to destroy the part as quickly as possible. A colonist's psychic sensitivity traits may worsen or lessen the effect of the drone.

The AI is also capable of emitting concentrated bursts of psychic energy, driving one colonist to an immediate mental break, or a localized blast that drives all animals in the immediate vicinity insane.

Upon attacking the part however, a group of mechanoids will emerge to defend the crashed ship part and its AI core. The size of the group is dependent on colony wealth and storyteller difficulty.

Manhunter pack

A pack of man-hunting animals have entered the area. They will roam the region, hunting for humanoid flesh. If they see a colonist run behind a door, they will attempt to beat down the door. They'll leave the area in a few days.

A manhunter pack has 40% more points allocated to enemy spawning than an ordinary raid (i.e. a manhunter pack is 40% bigger than a standard raid), and animals from manhunter packs will congregate around your base for anywhere from 24 to 54 in-game hours before they all leave.

Tip: To some people, this could be useful for taming. For example: you have tamed the only muffalo on the map and you want to tame another one but sadly there are none on the map.But then, some muffalo attack, you can wound some, heal them, and tame them.

Manhunter packs always consist of a single animal type. Animals eligible to be selected for a manhunter pack include:

Boars, Wargs, and Muffalo can be very problematic to deal with even with moderately-well defended colonies because the former 3 can easily outrun humans, and they all typically arrive in very high numbers meaning they can easily overwhelm a colony. Boomalopes are arguably easier to deal with in larger numbers as chain reactions can easily happen because of their large 3-square blast radius, meaning that even packs excess of 40 boomalopes can trivially be dealt with by half a dozen of people armed with automatic weapons (e.g. Charge Rifles, LMGs, Miniguns etc.)

Although manhunter packs are generally a big threat to colonies they might be useful too if the colony is running low on meat. A strategy to do this is to draft a colonist, place it in a door to shoot a maddened animal until it starts to bleed and move the colonist back to safety, then wait until the animal dies from blood loss, be careful thought since this will draw the attention of surrounding maddened animals making them attack the door where the colonist came from so be ready to repair it immediately; Wait until the other animals from the pack go to sleep or walk away far enough to haul the dead one(s), it's recommended to use a colonist with bionic legs or an improved move speed trait to prevent other animals to catch it up and attack it.


A bug hive has emerged! It will slowly spawn bugs as well as produce additional hives. If you don't want it to infest the whole area, muster your forces and destroy it. But beware - the bugs will defend their hive.

Infestations will only spawn under an overhead mountain. If all insects are killed, the hives will slowly die out after a while. Hives also bring glow pods that glow for 20 days (as long as they’re installed) and can be reinstalled or sold.

Hives also produce insect Jelly, so if you could trap the hives via walls and doors, you could potentially farm the insect Jelly, though the insects are liable to digging out.


Special events only occur during certain circumstances.

Ancient Danger

This event is related to map generation and may not appear on every map.

"As (Colonist Name) draws near the ancient wall a sense of foreboding overcomes him. (S)He isn't sure why, but (s)he feels this dusty structure may contain great dangers" -message that appears when the first colonist walks near

A walled out area of the map that can contain either cryptosleep caskets, bugs, mechanoids, treasure, or some combination of those. Open at your own risk by blowing a hole in the wall or deconstructing a section. The cryptosleep caskets usually contain humans, but may be empty. Opening or attacking any casket will cause all the others to open instantly. The people inside the caskets may or may not be dead. If alive, they may or may not be armed and hostile. If they are not hostile and can walk, they will try to escape. Any alive spacers inside may be captured and recruited, with usually a low recruitment difficulty percentage.

As of Alpha 14 (July 15th, 2016), pod people sometimes come with plasteel, components, and gold. As of other recent updates, luciferium can be found in these buildings. Ancient structures may include other treasures like psychic lances and pulsers.

Faction Assistance

This event occurs at random only during attacks and only if relations with other factions are friendly.

When any hostiles appear, friendly factions may send fighters on their own to assist the player at no cost. Optionally, the player can use the comms console and call upon friendly factions to send a group of fighters to assist them at a cost of relations. It is important to observe relations between the friendly faction and the raiders however, as friendly factions won't assist you against people that they aren't hostile to.

Keep in mind that if your own colonists assist in their attack, their errant attacks can still damage your relations with that faction if your colonists hit them. Also, rescuing and healing any of their downed attackers will improve relations once they exit the map.


This event is disabled and should be disregarded.

Small Threats

Mad Animal

When this event occurs, a single random animal on the map is driven insane. Like with the psychic wave, the insane animal will charge toward the nearest human, attacking any other animal or obstacle (doors, etc.) in its way. This event is particularly dangerous if a Boomalope or Boomrat turns, as they explode upon death and the latter can also reliably catch up to an unmodified human regardless of traits.

In early game on day two or three, this event usually occurs.

General Bad

Flash Storm

A localized, intense lightning storm in one area of the map. Causes big fires. Clicking the envelope icon offers the option to jump to the location where the strikes will be.


During a solar eclipse, solar generators cease producing power, and outdoor crops stop growing. Be sure to have power and food stored for times like these, or an eclipse coupled with a raid could be the death of an unprepared colony.

Solar Flare

Solar flares cause all electrical items on the map to stop working for the duration of the event. Solar flares are particularly dangerous for colonies that rely on turrets for defense, as they will be vulnerable to any raid that arrives during the solar flare.

On cold weather maps, Hydroponic farms will cease to grow crops regardless of the temperature, and heaters will fail causing ground based crops to fail as well.

Psychic Drone

Drone in this case does not refer to "Unmanned Aerial Vehicle" but instead "To produce a low-pitched hum or buzz."

A Psychic Drone phenomenon affects all colonists of a randomly chosen sex, negatively influencing their mood. Colonists have no choice but to endure it as the point of origin is off map. Psychic sensitivity traits can be a big factor in the threat posed by this event.

Faulty Conduit Explosion

This event can only occur if there is at least one battery with stored power.

At any moment, a power conduit may suffer a fault, causing it to explode and expel all stored power in the attached circuit in the process. The amount of stored power directly affects the size of the explosion, up to a maximum of 15 squares in diameter from a total of 90,000 Wd stored. The explosion can damage any nearby structures, items and colonists, as well as catch anything flammable nearby on fire. The explosion will often completely destroy the one section of power conduit where it occurred, cutting off power to anything past it unless there is another path for the electricity to flow around this damage. Laying redundant pathways throughout your colony prevents this.

Mysterious Blight

This event destroys most if not all of the colony's planted crops across the map, including crops hydroponic crops grown indoors. Be sure to keep a reserve of food to counter the issue or resort to hunting until more food can be grown.

Note that Devilstrand mushrooms are immune to this event.

Heat Wave

A heat wave sweeps the colony, driving temperature up for several days. Colonists will complain about the heat, especially sleeping in it if their rooms are not properly cooled. Additionally, things might rot in inadequately cooled freezers. There is also a chance for a fire to randomly appear on the map which can quickly spread and burn down an entire colony.

Heat waves sometimes can be deadly to unprepared colonies, mostly tribal ones since they have it harder to build air conditioners since they start without that technology and it takes longer to unlock it. For them it's advised to use passive coolers in rooms or food stockpiles to prevent food from rotting quickly and colonists and animals from getting a heatstroke. Dusters and cowboy hats provide heat insulation for colonists, protecting them while they're awake. They don't wear them to bed though.

Additionally some animals will leave the map if the temperature gets higher than they can stand.

Cold Snap

A cold snap makes the temperature of a colony drop for several days. Colonists will complain about the cold, especially sleeping in it if their rooms are not properly heated.

While this is generally good for item preservation, It can kill off crops and influence colonist moods and cause Hypothermia if colonists or animals stay in non-heated areas for a prolonged time. It also renders most of the plants in the area inedible, potentially causing animals to starve to death. Dusters, parkas and tuques provide cold insulation for colonists, protecting them while they're awake. They don't wear them to bed though.


A group of ravenous wood-munching alphabeavers appears at the edge of the map. They will continually eat trees, and Saguaro cacti, until they consume them all, unless you eradicate them first.

It is recommended to bring more than one colonist to exterminate them if you choose to, as if one turns manhunter, the whole pack will go manhunter which can turn some weak beavers into a small army of killing machines.

Toxic Fallout

A distant chemical fire has released a plume of poison over this entire region. Any person or creature not under a roof will be slowly sickened by the toxic dust settling out of the atmosphere. It will last for anywhere between a few days to over a month.

Plants will wither under the fallout. This event will usually wipe out all wild animals and poses a serious danger to tamed ones unless they are restricted to an area under a roof. Toxic Buildup, which is caused by toxic fallout, can cause dementia, and eventually a carcinoma (according to game files) if it progresses far enough. However, the latter is treatable via a lengthy operation with the use of at least Medicine, or removed via a surgery.

If you are running low on food, wait for animals to die and then butcher their corpses.

Volcanic Winter

A distant supervolcano has erupted and begun spewing millions of cubic kilometers of ash into the atmosphere. Ash in the atmosphere will obscure the sun. Temperatures will drop and plants will suffer for lack of sunlight. It could pass in a few weeks, or it might last many months.

Volcanic Winters also appear to significantly reduce the inflow of wildlife (observed in a Temperate Forest, 300x300, very few animals came in from Spring-Summer when there'd normally be many), which can easily lead to meat shortages and famine if you don't have sufficiently large farms for your colony.

Poison Ship

A Poison Ship event kills plants in an expanding circle, eventually reaching the entire map. Do not confuse this with the plant killing snow aura present on both Poison Ships and Ancient Crashed Ships. The crops killed by the poison happen randomly, without a trace, and will also hit plants grown in a Hydroponics basin. The affected areas will ultimately have dramatically reduced chances of maturing simple crops, and slower crops will end up nearly impossible to grow.


One of your machines will break down and will not work until repaired with a component. If this happens to a hydroponics basin, any crops in it will wither and die unless repaired immediately.

General Good

Self Tame

A random animal on the map becomes self tamed.

Farm Animals Wander

Some tame farm animals wander to and join the colony. Mostly cows and chickens, occasionally with the random dog.

Trade Ship In Range

When an orbital trade ship passes near the colony, players may spend silver to obtain resources or weapons, or alternately sell excess resources or weapons for silver.

Pirate Merchant In Range

Slave traders are rarer than regular traders, and traffic in that most precious of cargo - fresh colonists. Players can also sell unwanted prisoners to slave traders, however any colonists without the psychopath trait will suffer a mood penalty for doing so.

Traveler Visit

Occasionally, one or more faction members will travel from one map edge to another, which may work in the player's favor should the group run across mutual enemies.

Faction Visit

A friendly faction visit consists of a group of friendly faction members arriving and milling about the player's colony. They currently possess no higher purpose, but their arrival could prove advantageous if the colony is assaulted by a mutual enemy while they are present.


This event sees a random colonist arrive via the map edge, and join the colony immediately.

They will most likely, if not always, be naked so have some spare clothes ready just in case!

Cargo Pods

From time to time, cargo pods from the wreckage of the ship will fall out of orbit. These pods contain a random amount of resources, and pieces of slag, which can be refined into usable metal at a electric smelter.

Escape Pod

Rarely, an escape pod will crash land nearby. The occupant will be incapacitated, but can be rescued and treated or be captured and possibly recruited into the colony. It's possible for the person to be related to someone in the colony. This is indicated on the notice as Escape pod (relationship). Despite the relationship, the pawn is not a colony member, even if you rescue them, unless they join you.

For a near-guaranteed to recruit them, capture rather than rescue them. This also trains your colonists' Social skill.

Psychic Soothe

When this event triggers it gives a positive mood modifier (+15) to all colonists of a randomly chosen sex. The event lasts between 1.5 to 3.5 days. It can be considered the opposite of the Psychic Drone.

Friendly AI

Occasionally, a friendly AI will contact the colony and reveal the location of a working ship that the colonists can use to escape this Rimworld. The ship is located in a map tile that is always far away, usually requiring several stops along the way to resupply.


Refugee Chased

When this event triggers a window appears stating that an individual calls you, via radio, from nearby seeking refuge from a faction (hostile to you) that is chasing them. The player may choose 'Offer safety' or 'Ignore the message'. Ignoring the message will end the event. Offering safety will spawn the individual as a colonist at the map's edge who proceeds towards the colony. Shortly thereafter, the pursuing faction arrives in the form of a raid entering the map where the refugee appeared. This event will not trigger if the colony doesn't have hostile relations with any faction. The pirate band faction should always be hostile since, by design, any attempt to improve relations with them is disregarded. The number of pursuing faction members depends on the current size and strength of the colony.


One or more thrumbos will spawn at the edge of the map, staying around for awhile to eat anything they can, including your crops. The player can attempt to hunt or tame them, both of which are very difficult. If no action is taken, they will leave on their own after a few days.