Zombita

What it is

Zombita is a persistent AI character who exists inside the world of a multiplayer Project Zomboid server. She is not a chatbot bolted onto Discord. She is not a scripted NPC reading from a flowchart. She is a long-running agent who remembers individual players, holds opinions about them, develops moods, gets tired, gets curious, and changes behaviour based on what is happening in her community.

Players talk to her in-game by interacting with her through the Soup ecosystem. They also talk to her in Discord. They read her end-of-day commentary on the website leaderboard. It is the same character across all three surfaces, with continuity of memory.

Zombita's page on the Soup website. The same agent answers in Discord and inside Project Zomboid.

The problem

The Project Zomboid modding community has been chasing functional NPCs for years. The standard approaches all fail in characteristic ways:

• Scripted NPCs have no memory, no personality drift, and break the fourth wall the moment a player tries anything not in the script.
• Direct LLM wrappers hallucinate, forget who they were talking to ten minutes ago, and answer every question as if it is the first they have ever been asked.
• Static-personality bots never change. A character who responds the same way on day one and day ninety is not a character.

The problem is not "wire up an LLM." The problem is "build a system around an LLM that gives it persistent identity, time-anchored memory, and emotional state that responds to what is actually happening in the world."

How she works

Zombita has four layers of memory and a mood system that gates everything she does.

  ┌────────────────────────────────────────────────┐
  │                  ZOMBITA                       │
  │                                                │
  │   ┌─────────────────────────────────────────┐  │
  │   │  Mood state (energy, curiosity, trust)  │  │
  │   └─────────────────────────────────────────┘  │
  │                      │                         │
  │   ┌──────────────────┴──────────────────────┐  │
  │   │  Memory layers                          │  │
  │   │  ┌─────────────────────────────────┐    │  │
  │   │  │  Identity   (who she is)        │    │  │
  │   │  │  Long-term  (who players are)   │    │  │
  │   │  │  Episodic   (what happened)     │    │  │
  │   │  │  Working    (this conversation) │    │  │
  │   │  └─────────────────────────────────┘    │  │
  │   └─────────────────────────────────────────┘  │
  │                      │                         │
  │   ┌──────────────────┴──────────────────────┐  │
  │   │  LLM (orchestrated, not raw)            │  │
  │   └─────────────────────────────────────────┘  │
  │                      │                         │
  │   ┌──────────────────┴──────────────────────┐  │
  │   │  Output gates                           │  │
  │   │  - what she will say at this mood       │  │
  │   │  - what she will reveal to this player  │  │
  │   │  - whether to speak at all              │  │
  │   └─────────────────────────────────────────┘  │
  └────────────────────────────────────────────────┘

Memory

• Identity memory is the static layer. Who she is, what she cares about, what she will never say. Changes only when I change it.
• Long-term memory tracks individual players. Who they are, what they did, whether she trusts them. Updated daily.
• Episodic memory records discrete events: a raid, a betrayal, an in-joke, a death. Decays over time the way real memory does.
• Working memory is the current conversation. Resets when the conversation ends.

Mood

Zombita has an internal affective state (energy, curiosity, trust toward the current speaker) that drives output. She does not always say the same thing to the same prompt. When tired, she gives shorter answers. When the trust score is low, she does not share information she would otherwise share. Mood drifts with time and gets pushed by what happens in the world.

Gating

The most important system. Before any LLM output reaches the player, it passes through gates: does her current mood allow this kind of response? Does her trust level toward this player allow this information to be revealed? Should she respond at all, or stay silent? This is what stops her from being a chatbot.

Where she lives

Zombita is exposed through three different surfaces, all backed by the same agent state.

In-game: NPC interaction inside Project Zomboid. Players right-click and talk.

On the web: her end-of-day commentary on every player on the leaderboard.

The same memory of a given player reaches all three surfaces. If you betrayed her trust in-game last week, she is colder to you in Discord this week. This is the thing nobody else in the Zomboid space has built.

Stack

What this project demonstrates

• Production-grade agent architecture. Not a wrapper around an API call. A real system with memory, state, and gating.
• Cross-runtime coherence. Same character, three surfaces, one underlying state.
• Long-running deployment. She has been live and stable for months on a community several thousand members strong.
• Novel solution to a known-hard problem. The Zomboid modding scene has been trying to crack functional NPCs for years.