Raids and Events
How the storyteller delivers raids, mechanoids, infestations, fallout, and Anomaly threats, and how they scale with your wealth.
Threats in RimWorld are not scheduled on a fixed timer. An AI storyteller reads your colony and generates events to produce a dramatic arc of tension and relief. It spends “raid points” to buy attackers, and the single largest input to that budget is colony wealth, followed by colonist count. Understanding the threats means understanding two things at once: what each one does, and why it got as big as it did.
How threats scale
The storyteller calculates raid points, then spends them. For the 1.x line, the RimWorld Wiki confirms the formula as Raid Points = (Wealth Points + Pawn Points) x Difficulty x Starting Factor x Adaption Factor. Storyteller wealth counts item wealth and creature wealth at full value and building wealth at half. Wealth points climb on a curve: zero at 14,000 wealth or below, 2,400 at 400,000, 3,600 at 700,000, and 4,200 at 1,000,000, above which wealth adds nothing more. Each free colonist adds pawn points, from 15 at very low wealth up to 200 at a million.
Two dials soften the early and post-loss game. The starting factor sits at 0.7 through day 10 and ramps to 1.0 by day 40, buying you a grace period. The adaption factor is a safety net, not a difficulty ramp: it lowers raid size for a while after colonists are downed or killed, then returns toward normal. Raids are bounded at a minimum of 35 points and a maximum of 10,000, and Randy Random alone multiplies raid size by 50 to 150 percent after the cap.
| Input | Effect on raid size |
|---|---|
| Wealth (to 1,000,000) | The main driver. Buildings count at half, stored items at full. |
| Colonist count | Second driver. More free pawns, larger raids. |
| Difficulty | Flat multiplier, 0.10 (Peaceful) to 2.20 (Losing is fun). |
| Starting factor | 0.7 early, 1.0 by day 40. |
| Adaption factor | Drops after losses, recovers toward normal. |
Hoarding is the quiet way to lose. Stored resources count at full wealth, so large silver, steel, and luxury piles inflate the next raid faster than they help you fight it. Keep effective wealth in weapons, armor, and defenses, and sell the dead weight.
Raids
Raids are the core threat: hostile human factions, usually pirates or hostile tribes, sometimes the Empire, coming to attack. How they arrive matters as much as how many there are. A standard assault walks in and fights. A drop-pod raid lands inside or on top of your base and skips the perimeter entirely; center drop-pod raids are somewhat smaller than their points would suggest. Sappers mine or destroy walls to reach a target, often a bedroom, taking the shortest path rather than your intended entrance, and they come in smaller numbers. Breachers carry breach axes or arrive as termite mechanoids that smash through walls in their path indiscriminately, a deliberate counter to pure turtle bases. Sieges land with supplies, build sandbags and mortars at range, bombard you, get resupplied, and assault directly if their mortars are destroyed.
No single defense stops all of these, which is why a killbox needs interior fallback positions and anti-siege tools alongside it.
Mechanoids
Mechanoids are the late-game robotic enemy. They arrive as raids, and as mechanoid clusters: a dropped encampment of mech structures and units that stays dormant until provoked or until a timed activation. Left alone, mechanoids persist indefinitely, and tough units like centipedes and scythers make them a serious step up from human raiders. With Biotech, mechanitors command their own mechs as a mobile army. Anomaly and Odyssey add mechanoid-related content, and Odyssey hides a mechanoid lair to find in orbit. The practical rule is simple: do not poke a mech cluster before you are ready, because many of them will wait for you.
Infestations and environmental threats
Infestations are insectoid hives that spawn under overhead mountain roof, in roofed rock areas above roughly minus 8 degrees Celsius. They keep producing megaspiders, spelopedes, and megascarabs until cleared, which is why mountain bases keep cold dead zones and thick walls to control where hives can appear.
The weather has its own arsenal. Toxic fallout poisons everything outside unroofed cover, accumulating toxic buildup in colonists, animals, and plants over a wide span of days (reported roughly 2.5 to 10.5), forcing the colony indoors and straining food. Biotech adds pollution and toxic wastepacks as a related mechanic. Beyond that, cold snaps and heat waves bring hypothermia and heatstroke, flashstorms bring fire, eclipses and solar flares cut power, volcanic winter chills everything, and blight destroys crops.
Diseases are a threat in their own right. Plague, malaria, sleeping sickness, flu, and gut worms all appear, and untreated wound infections kill. Humid biomes like tropical rainforest run higher disease rates, and survival is an immunity-versus-severity race managed by medicine, doctoring skill, and bed quality.
Anomaly and Odyssey threats
The Anomaly DLC adds horror-themed monsters tied to the void monolith. Entities can be fought or captured and studied in specialized containment, and their escape intervals depend on how the holding cells are built. The roster includes shamblers (undead-style hordes), fleshbeasts, the metalhorror (a hidden parasite), sightstealers, noctols, and the nociosphere, plus rituals like void provocation that deliberately summon entities. Anomaly can be dialed down or off through its ambient horror and intensity settings for players who want the base game’s threats without the horror.
Odyssey adds environmental threats tied to its new biomes and travel: lava flows and falling volcanic debris on lava fields, toxic rain in the Scarlands, blizzards on glacial plains, space vacuum and depressurization in orbit, and new hostile wildlife and underground insects.
Reading the pressure
The through-line across every threat is the same tension the whole game runs on. Your wealth rises whether you want it to or not, and the storyteller spends that wealth against you. A colony that grows lean, keeps value in things that fight back, and hardens against every raid type (not just the walk-in) stays ahead of the curve. A colony that hoards, over-decorates, and relies on one clever trick gets a raid it cannot answer.
Next: the colonists and mood deep guide for the pawns who fight these threats. For the wealth mechanic in full, see the research and economy deep guide. For defenses, see the killbox and defense cheatsheet.