Starting from the third day of the event, there will be an unpredictable zombie siege each day, the intensity of which will depend on the number of members at the base, the number of buildings, and luck.
During the event, players can enter the Underground City dungeon to fight zombies, blow up equipment, gather materials, and build their base. All players share one Underground City which is vast, making encounters with other players rare.
Important Notice: Fortress agents will enter the dungeon at eight in the morning on the third day of the event, with the mission to hunt down players. They have three privileges: first, they can teleport to any portal every five minutes; second, they can use a search function once a day to locate any base member's position in the Underground City; third, they can use weapons and items purchased with points.