What If a Virus Got Out?
Design a pathogen. Pick a country. Watch the world burn.
The Pandemic Simulator is a free online game that lets you design a custom pathogen and release it into a simulated world of 8 billion people across 20 countries. Using a real SEIR (Susceptible-Exposed-Infectious-Recovered) epidemiological model, the simulator shows how diseases spread through populations, how governments respond with border closures and lockdowns, and how random mutations can change the course of an outbreak. Adjust the R0, lethality, incubation period, and mutation rate to create anything from a mild cold to an extinction-level plague.
The simulator models disease transmission using the same mathematical framework used by real epidemiologists. Each simulated day, the engine calculates new exposures based on the pathogen's R0, the ratio of susceptible to total population, and healthcare quality. The virus spreads between countries through simulated international travel (0.1% of infected travelers per day). When infections reach critical thresholds, AI-controlled governments close borders and implement lockdowns that reduce transmission by 60%. Mutations can randomly alter the pathogen's characteristics over time, making the outbreak unpredictable.
A pandemic simulation game lets you design a custom pathogen — setting its R0, lethality, incubation period, and mutation rate — then release it into a simulated world. The simulator uses real epidemiological models to show how diseases spread, how governments respond, and how mutations can change the course of an outbreak.
Pandemics spread through person-to-person transmission, quantified by R0 (basic reproduction number). The disease moves through stages: exposure, incubation, infectious period, then recovery or death. International travel carries the virus across borders, while government interventions like lockdowns and border closures slow transmission.
The original SARS-CoV-2 strain had an R0 of about 2.5-3.5. The Delta variant reached 5-6, and Omicron 8-15. For comparison, measles has an R0 of 12-18 (highest known), seasonal flu is about 1.3, and Ebola is 1.5-2.5. You can simulate all of these in our Pandemic Simulator.
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Last updated: March 2026 · whatifs.fun — Free interactive games, experiments & simulations