Battlefield of Ten Thousand Races: from Burrow to Fortress

When all mankind was thrown into the Arena of Ten Thousand Races, Lin Feng started with only a pair of underpants. When he woke up, he was standing on an ice field at minus 40 degrees Celsius. There are no weapons, no teammates, and no novice gift packs. There is only a line of cold text in front of me: [A random environment has been generated: the extremely cold wasteland. Survival rate: 3%. [Mission: Survive tonight. Lin Feng looked around - the wind and snow, the cliffs, the howling of unknown creatures in the distance. Unarmed. Body heat is being lost. It's getting dark. He had to start from scratch. He peeled off the tree bark with his bare hands, sharpened his bone knife with gravel, and dug out the first shelter on the frozen soil. When the blood moon rose on the first night, he huddled in the hole he dug, listening to the footsteps of predators from all races outside, gritted his teeth and piled stones at the entrance of the hole. This is only the first day. The system prompt sounds again: [Random environment has been generated: Extremely cold wasteland] [Regional Difficulty: Level C] [Estimated survival rate: 3%] [Mission: Survive tonight] [The safe house has been unlocked. Level: 1. [Required for construction: wood*80, stone*20, fiber*20] [Warning: In seven days, the beast tide is coming. Lin Feng looked at the piles of rocks on all sides and the endless ice fields. Some people died of thirst in the desert, some were devoured by poisonous insects in the rainforest, some built wooden houses but were trampled down by the first wave of beasts. . They were both struggling on the edge of survival, but Lin Feng's goals were different. What he wants to build is not a shelter. He wants to build a fortress that will never be breached on the battlefield of all nations. Forges were lit, defensive towers erected, and walls raised. From caves to stone huts, from stone huts to fortresses, from fortresses to mobile war fortresses—