Purge 101: How it works and other things you should know


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We get several questions related to The Purge from players so we wanted to take a moment to run down exactly what The Purge is and how it works. Hopefully this will give you a better understanding of this game mechanic.

What is the Purge?

The Purge is when hordes of NPCs come to attack your base to destroy you and your buildings. The difficulty of The Purge will depend on where you’ve built and the server settings. The Purge is considered a PvE feature and could attack you on any official servers. In single-player games they are turned off by default and need to be turned on in the server settings.

What causes the Purge to attack?

If you open up your inventory, you’ll see a bar beneath your character. This is the Purge Meter. As you play the game (gather resources, build, kill NPCs, explore the word) it will start to fill up. Once it reaches the first line you can be attacked by a Purge. It won’t happen automatically when you go over the threshold, but as long as your Purge activity score is above it, there’s a chance for it to happen. Keep in mind that it’s always a chance, not a guarantee.

The system works on a periodic scoring system. If anyone in a clan performs an action in that period – e.g. kill a player, build something etc., then that event is added to the list of events that have been performed in that period. The amount of times an action is performed, and the amount of players that perform it, is irrelevant. A clan that kills 1 NPC will receive the same score as a clan that kills 1000. Every update cycle, the Purge events are added together and the score is added to the Purge meter. All Purge events are then cleared for the start of the next period.

So, who gets attacked then?

The system is set up to choose a player (or clan) at random. If you are on a dedicated server or local game, and you are the only one playing, the purge will only pick you. But on a server with, for example, 10 clans, 4 of which are above the threshold, you have a 25% chance to get it if you are among the 4.

On official servers’ purges will only trigger during “Purge Time” which is a subset of prime time, “Purge Time” is between 6 PM and 10 PM local time (18:00 - 22:00, all days. Admins of private servers will be able to adjust this time either through the server setting GUI or modifying the serversettings.ini files.

Do you have a list of all the Purge settings?

Yep!

SETTING Serversettings.ini NAME Effect
Enable Purge EnablePurge Unchecking will completely disable purge events.
Purge Level PurgeLevel Raising this increases the purge difficulty level. Level zero will turn purge system off.
Purges per day PurgePeriodicity Raising this increases the number of times a purge will be triggered in a real day. The actual number of purges is also dependent on the various settings below.
Restrict Purge Time RestrictPurgeTime If flagged, Purges will be restricted to set times.
Purge Time Restrictions PurgeRestrictionWeekdayEnd The Purge will only take place during the times specified.
PurgeRestrictionWeekdayStart
PurgeRestrictionWeekendEnd
PurgeRestrictionWeekendStart
Purge Preparation Time PurgePreparationTime Raising this increases the time in minutes between the purge warning and the start of the purge.
Purge Duration PurgeDuration Raising this increases the maximum time the purge will last. If you kill all of the waves a Purge can complete sooner
Minimum Number of Online Players MinPurgeOnlinePlayers Raising this will make purges only occur when the set number of players are online. If set to zero, the Purge will attack any clan above the Purge meter threshold (offline Purges)
Allow Building AllowBuilding If flagged, building is allowed during purges.
Purge Meter Trigger Value ClanPurgeTrigger Raising this means more increases the amount of actions clans or players can do until they are eligible to be purged. In general, the higher the number, the longer a clan needs to be active in order to trigger the Purge
Purge Meter Update Interval ClanScoreUpateFrequency This is the interval that clan Purge events are aggregated, and the scores are added to the Purge Meter. Lower numbers will raise the clan meter more quickly.

I tried using the admin commands and nothing happened

Those are debugging commands added for the development team. They were never meant to instantly activate a Purge (there could be a several minute delay before a Purge even starts). They’re not guaranteed to trigger a Purge either (the Purge analysis could fail), and the Purge might happen in a different location. Those commands need to be used in conjunction with other debugging systems to be of any use, e.g. monitoring log output, breakpoints in code, showing Purge debug info, etc.

Support for these commands for people outside of the dev team was never planned and they are not meant to be used in the live game. The dev team are using the commands without issue for the purpose they were created.

My Purge Meter is full, but nothing’s happened. What gives?

Even with a full Purge Meter you might not get purged right away. You may even get purged while you’re offline, so keep those defenses up!

Where are the mobs spawned and what are they heading towards?

They determine their location for spawning based on their ability to path to their targeted object, and then spawn in that area. They will target your buildings and placeables.

What influences which mobs spawn?

Difficulty affects which waves are picked to Purge. Higher difficulty levels have more powerful NPCs, spawn more waves and spawn more bosses. Waves are configured to be relevant to particular areas of the map. Some Purges are configured to have only one wave, others have several waves. Higher difficulty levels have a weighted chance of spawning more powerful Purges. It is still possible to spawn a level 1 Purge even though the difficulty is set to level 6.

What influences the time before arrival and between waves?

The server settings determine how much time you have to prepare after a Purge announcement. The same goes for how long the Purges last and how many waves there are.

What about Purge difficulty?

The Purge has 6 difficulty settings:

  • 1,2 are used around the southern river (can be resisted with T1 buildings)
  • 3,4 are used in the center of the map and the swamp (can be resisted with T2 buildings)
  • 5,6 are used in highlands, frozen areas and volcano (you should have T3 buildings to resist them)

Fixes in Purge System Updates

  • Purge clan meters were being incorrectly raised. This meant that all clans on a server could reach purgable level without having to do much
  • In the latest updates, inactive clans’ Purge meters will decrease over time. This will result in less active clans falling below the Purge threshold, and more active clans being purged more frequently.
  • Purge analysis was failing due to areas not having enough time to be brought up to the required level of detail for analysis. This has been fixed so there should be less failed Purges
  • Players were getting Purge notifications before we determined that a Purge could happen, and then instantly failing. This has been fixed. So, you should only be notified when a Purge will actually happen.
  • It is currently possible to build Purge proof bases that will never be Purged, as analysis has determined that the Purge would be ineffective. We hope to identify more of these camps, and build better strategies to attack them. To have a better chance of being Purged, give your settlement some form of ground access to an open area.

Known issues

There are some known issues with the Purge that we’re working on smoothing out:

  • A Purge doesn’t strike anyone on the server, even with full Meters, for several days
    • This could be a consequence of a server having thousands of clans registered in the database. The Purge targets a clan at random
  • The Purge meter doesn’t tick up as intended on dedicated servers
    • We are working on this issue

Is it me, or did my purge meter freeze?
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