Pandemic of the Forgotten Virus

In late 20XX, due to the spread of a mysterious virus, humanity has declined severely. People are dying left and right and the remnants of humanity are forced to fully lock down themselves in their homes, waiting for extinction. The rich population of the world built large floating islands in the sky to escape the virus, leaving the less fortunate down below. After a hundred years, a sudden breakthrough happened, technology to build floating islands became much cheaper and more available to the general public. Tired of their fate, people started building floating islands left and right without...