The Purge mechanics

Where you establish your base will determine what sort of NPC enemies arrive during the Purge: above, you can see frost giants lumbering out of the snowy mountains to attack a player base, and if you build in the lowland swamps you may find yourself being swarmed by angry gorillas.

The difficulty of the Purge also depends on how close you build to the most valuable resources on the map. So, building close to a valuable resource may give you an advantage over other player clans on the server, but the Purges you experience will be more challenging. Purges will happen both on PvP and PvE servers, and their frequency can be determined by the server admins. They can also be entirely disabled by the server owner, or scheduled to take place at certain times or days, such as on the weekends when the most players will be available to deal with them.