Microsimulation is like a tiny game where you create a world and watch what happens when different things happen in it. You give the game different rules like how people react to different things, and then watch how things change as you let the game run. For example, you might set up a game where people move around in a city and work different jobs. You could then watch what happens when a new law is passed or when people decide to leave the city. The game would change based on the rules you set earlier, and you would get to see what kind of effects the rule changes have!