Info (must read)

Many years after most of Earth was devastated by a nuclear bombing, only one city managed to remain intact: The city of Yusso. 85% of humanity was destroyed, and the total population of mankind was 300,000 people.

Morale was quickly dropping, people were dying and becoming sick, the crime-rate was off the charts mostly due to insanity. The leader of Yusso turned to rash decisions and after 3 years, he and 150 smartest engineers built a huge spider-like robot and sent it out into the waste-lands to clean up everything.

It didn't work.