Simulation: Working Tirelessly to Save the World

(Be careful when entering the doomsday text) Two and a half years ago, a sudden appearance of a monster disrupted the world. At first, humans could use weapons to resist the attacks of tide monsters, but as more advanced tide monsters joined the battle, the battle gradually tilted towards them. With the addition of high-level tide monsters, humans have also developed the same abilities as them. In the end, humans could only shrink into one stronghold after another, and those high-level tide monsters all disappeared as if they had evaporated. Only a large number of low-level tide monsters were left.