The world was a steampunk world. Most technologies were motivated by coal but still, there were some remaining technologies powered by electricity—a kind of energy came from prehistoric civilizations. The most common thing used by explorers was beacons. These were small boxes, connected to the satellites launched by prehistoric civilizations. These beacons did save some lives but for some times, but in other cases, people could not get access to the places of the beacons at all. There were three villages in the story, and each of the village discovered a way to save the world (although they were proved to be useless at all). One decided to save the world by digging inside the earth and figuring out what happened inside the mantle. Another decided to burn tons of coal to increase the amount of greenhouse gas in the atmosphere to save the world. They can give everything for their dreams. The third village focused on biotechnology, and they decided to find a way so people would not feel cold in the snowstorms. However, it turned out that even if people don't feel the cold anymore, they still freeze to death. In both three villages, there was a huge smelter in the center of the village, providing heat to all the villagers and powering the facilities. Water was burnt into gas in the smelters, and then was transformed in tubes. Houses were built around the smelter, and the village was in the shape of a circle. Sometimes the tube may break, and the hot gas would leak out. Some unlucky villagers would be killed in the middle of the night without even waking up. For most of the villages, they have a mine which could provide them with coal in the cold climate. However, there were some village which did not contain a mine. They had to trade with others to make a living. It was weird that the second village did not have a coal mine at all, but this may be the explanation of why they were crazy about coal. The center of the earth was cooled and earth lost its eternal heat, and that was the reason why the global temperature turned down in decades and civilization collapsed. Life on Earth evolved the ability to detect the amount of radioactive material on earth. As a result, most plants, sensing the disappearance of radioactive material from the Earth's interior, began to secrete a special protein that allowed them to survive the cold. However, for most animals, because radioactive materials are harmful to them, they tried to stay away from the radioactive source as much as possible, and this ability to sense radioactive materials gradually disappeared. Even if the third village managed to restore some of their abilities, humans would still not survive the winter. Steam generator: the steam generators were highly energy-efficient and they could transfer the energy in the coal completely into heat, with little or even no energy lose. Thus, a small amount of coal can turn a large amount of water into gas. All the weapons were powered by steam.