So, this is our very first model, S-I-R. It only takes one infected person to set off a chain reaction. The red wave climbs fast, showing loads of new cases at once. At the same time, the green line drops, because fewer people are left to catch it. The blue curve shows the people who got sick, recovered, and are now immune. In this example, the spread factor is 2.2, so each infected person passes it on to a bit more than two others on average. That is why the outbreak takes off so quickly. In Explore Mode, you can use the Contact Brake to bring that spread factor down and see what it does to the wave. That will help you get ready for Challenge Mode.
