After the player enters the safe house, he must first upgrade the workbench, bed and cooking utensils to the full level, and then there will be a red button. After meeting the upgrade conditions, click the button to upgrade the safe house level. "Survivor: City in Danger" is a horizontal version of the Roguelike survival sandbox mobile game developed by Temple Games and published by Jedi Games. In the game, players need to survive in a city full of zombies. Each zombie has different characteristics, and players need to deal with them by observing the zombies. The game is set in an apocalyptic world. In the context of the zombie massacre game, the survival story is triggered by players who are survivors seeking to escape from the dead: If you are in the apocalypse, zombies are full of the entire city, and you need food and weapons. Find it yourself. All you can do is survive as long as possible and try your best to escape from the city.