 The game takes place in fictional Empire City ( based on New York City ) , laid across three islands : the Neon District , where many businesses and entertainment venues are located , the Warren , the slum where goods are shipped into and out of the city , and the Historic District , the smallest of the three islands . The districts are connected by bridges , and each district has its own elevated train system . At the start of the game , six blocks of the Historic District are wiped out by an explosion from a bio @-@ electrical device called the Ray Sphere . A plague develops soon afterwards , forcing the government to quarantine the region . In doing so , they block the only bridge to the mainland from the city , causing societal collapse within the isolated city . 
