Project Zomboid New NPC System and New Mechanism Analysis

Fans have been waiting for the NPC system of Project Zomboid for a long time. From recent news, it seems the NPC system is coming very soon! Here, I will provide you with a complete and in-depth analysis regarding the new NPC system and its mechanisms!

About the New NPC System

The developers have gone above and beyond in implementing the lore for new NPCs. This is apparent from the depth they have added in their interactions. NPCs added in Build 43 will advance their storylines without having any encounters with the player. If an encounter happens, the storyline of the NPC will change.


Take for an example, an NPC with a family of four who had to take one of the family members to a hospital. But they had to go on foot because of a traffic jam. Now, if the player encounters the NPC while driving a car, a set of events will unfold.

On the other hand, if the player encounters the NPC while being on foot themselves, an entirely different scenario of events will trigger. There will be multiple ways of interacting with NPCs. This can have different effects on their storylines depending upon the actions you take.

Zombie Refresh

The in-game zombie refresh can be changed through the “Sandbox Settings”. Here, the “Refresh Interval” setting can be adjusted.

This changes the frequency by which zombies will refresh. By default, the refresh interval is measured in hours and is set to 72. Meaning one refresh will happen every 3 days.


Some newcomers might be worried that this mechanic could lead them to go out of the range of the fixed refresh frequency. Rest assured, this will not happen. Once you have established your home, you will have more than ample time to make your surroundings airtight, so as to ensure no zombies are spawned nearby.

Furthermore, zombies will not be allowed to spawn inside your home environment. More detailed information regarding this can be found in the zombie refresh mechanism research post.


Also relating to this experience is another issue that players face. Sometimes, you might use gunfire or horns to attract zombies, kill them and clean up the area. Afterwards, once you go ahead with your operations in the area, you’ll find that there are still zombies present.

and if you use gunfire or a horn, it still attracts zombies even though you already cleared the area beforehand! Is it because they keep refreshing themself? Maybe a bug!?


Well, that’s not entirely true. Gunfire, or a horn, doesn’t pull zombies present in an area over to you all at once. There can be individual zombies that were not initially pulled over to you, or were listening in another general direction.

It’s also possible that the zombies were walking away from you when you initially made the noise and so, didn’t come over to you. However, upon using gunfire or a horn for the second time, they got attracted to the noise.

Zombie Migration Mechanism

In addition to this, there is an extra mechanism present in the game referred to as the “Zombie Migration Mechanism”. According to this, zombies will take up a fixed amount of time in pre-determined proportion to migrate from a dense area, slowly to a sparse area.


Think of it like a basket of sesame seeds. If you eat them from a corner, and then shake the rest of the basket, there will ultimately be sesame seeds present at the corners again!

This was a brief description of the new mechanics and NPC system being introduced to Project Zomboid. I hope it helped you out, and as always, good luck in your zombie killing endeavors!


   The new NPC system is coming very soon, and it looks to be a HUGE improvement over the old system. It will allow for more detailed storylines and more immersive gameplay experiences. I can‘t wait to see what kind of unique interactions we can expect!