Cancerous World

In 2150, the world's population exceeded 10 billion. At the same time, the global environment has undergone earth-shaking changes. The area of ​​desertified land has increased exponentially. Ninety percent of farmland has lost its farming function. The annual minimum temperature has increased by five degrees in one year. Surface freshwater coverage has dropped sharply. Sharply reduced food production and one after another viruses have caused the population to plummet from 10 billion to 4 billion. In order to survive, people have moved to big cities where resources are relatively concentrated. Within five years, urbanization reached an unprecedented 95%. Major cities expanded one after another and built huge city-states. For a time, thousands of city-states were formed on the earth. City-states competed with each other for resources and were independent of each other. More than 90% of society's resources were concentrated in city-states. Humanity entered the "city-state era".