Epidemiology

What this uses

Disease modelling is entity-level: each entity carries an activeDiseases array and an immunity record. Spread is computed pair-by-pair using proximity and transmission route. A full population simulation is driven by the host iterating over entity pairs each tick.

Disease profiles

Infection phase track — entity view

Entity lifecycle for the selected disease. Width proportional to duration.

Population spread — SIR model preview

Illustrative day-by-day infection spread in a population of 100 entities. Based on common_fever parameters with ~50% close-contact pairs per day.

Create / import custom disease profiles

Define a custom disease profile and save it to localStorage, download it as a TypeScript snippet, or import one from JSON. To add it to the codebase, export the snippet and open a pull request.

To add a custom disease to the codebase: download the .ts snippet, add it to src/sim/disease.ts, write a test in test/sim/disease.test.ts, then open a pull request ↗ with the title feat: add [NAME] disease profile.

Try this

1. Expose an entity: exposeToDisease(entity, 'common_fever'). Returns true if exposure succeeded (not immune, not already infected).
2. Step disease each tick: stepDiseaseForEntity(entity, delta_s, worldSeed, tick). Returns events (onset, death, recovery).
3. Model spread: call spreadDisease(entityMap, pairs, worldSeed, tick) per tick with an array of entity-pair objects.
4. Quarantine: simply don't include quarantined entities in the pairs array — they won't spread.
5. See MARSH_FEVER for vector-borne disease (triggered by MUSTARD_GAS-style hazard zone with diseaseExposureId).