S.I.R. is a simulation of a spreading pathogen within a group of people. Hundreds of people, represented as coloured dots, move around in a blue recatangular shaped boundary. At the start, one or two people are infected. Non-infected people are seen as a faint blue-green colour, while infected people are seen as a bold red. When one is infected, they can spread the disease to others through contact. Infected people, after a period of time, will either recover or die. Those who die will be removed from the screen, and those who recover are immune to the disease and are seen as a bright green colour. Several paramaters, such as population, number of people infected, r-value (the number of people an infected person will infect on average), number of people immune, and number of deaths are being recorded live and can be seen on a live chart below the simulation. Several parameters can also be adjusted before the simulation, such as population, probability of infection, death rate, lockdown rate, and vaccination rate. Currently, all parameters have been carefully adjusted and defaulted to best portray the current pandemic (COVID-19), but can be easily changed with the user's choice. Play around with the sliders and try different presets to see what happens!