In 2098, global warming of the earth caused harsh living conditions, and the scorching 85-degree sun burned the earth.
There are wastelands all over the place, and skeletons are everywhere inside the high walls with broken arms. The living environment is extremely unbearable. As a countermeasure to the scorching sun contrast theory that was concluded by scientists as early as 2050, it took a joint venture of scientists from various countries for 40 years to build a second habitat for mankind.
The surface of the earth is no longer suitable for human habitation. The coalition governments of various countries have worked together to build homes underground and continue to look for available resources for construction to improve the probability of human survival. The underground construction of various countries at 18,000 meters underground has almost hollowed out the outer shell of the earth. They have built underground fortifications that cover an area of enough for 5 billion people. Humanity has completely In order to return to the surface, the coalition government established a special expedition force with people from various countries to collect and find materials specifically for work on the surface of the earth. There are also many unknown creatures in the underground. Unknown creatures attack humans every six months. There is a risk of being killed at any time in the huge underground city.
