Awakening: Cutting the Universe from Earth

In the year 2205 of the Earth's calendar, in winter, Earth civilization encountered an unprecedented "severe cold". Invaded by "giants" and unknown "viruses", modern civilization has been severely damaged, and the human population has dropped by 60%. Due to the severe limitations of modern thermal weapons in the face of "giants", countless soldiers sacrificed their lives to defend their homeland. In the end, human civilization was forced to use nuclear weapons to defeat the first batch of "giants" that invaded the earth. As everyone knows, the first batch of "giants" that invaded the earth were only cannon fodder level 1 "Titans". Then more severe tests are gradually approaching the earth. What is the purpose of the mastermind behind all this, and how will mankind face it next...