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✓ VerifiedCreatures & NPCs

SecondBrain

by sailex · for Minecraft

AI-powered NPCs that chat and play like real players

28KDownloads
6 mo agoLast updated
LGPL-3.0-onlyLicense
FabricLoaders

About SecondBrain

From Modrinth

AI-powered NPCs that chat and play like real players

⚠️ Experimental Mod

SecondBrain

mod-logo

A Fabric mod that brings intelligent NPCs to your minecraft world. Create player-like characters controlled by LLMs that respond to your chat messages and perform basic player actions.

This mod works fully serverside. It must also be installed on a client for setup.

Requirements

  • Minecraft Version: 1.20.1/1.21.1
  • Running Ollama server OR Player2 App OR an OpenAi Key

Mod Installation

  1. Download the Mod:
  • Get the latest version of the SecondBrain mod from the Modrinth page.
  1. Install the Mod:
  • Place secondbrain.jar in your mods folder on your minecraft fabric server and client.
  1. Launch Minecraft:
  • Start the Minecraft client and the server, and you're ready!

Usage with Ollama/OpenAi

>Note: Player must be an operator to execute the following commands

GUI

  • Open the gui with the /secondbrain command and create/spawn, despawn/delete or edit the NPCs there.
  • Also edit the base configuration there.

~~Commands (Deprecated)~~

>~~Warning: This command uses default ollama/openai settings!~~

  1. ~~Spawn NPCs~~:
  • ~~Use the /secondbrain add <npcname> <openai|ollama> (currently only ollama is supported) command to create an NPC. (Example: `/secondbrain add sailex428 OLLAMA)~~
  1. ~~Remove NPCs~~:
  • ~~Use the /secondbrain remove <npcname> command to remove an NPC from the game world.~~

Interact with NPCs:

  • Just write in the chat to interact with the NPC.

Setup Ollama

Ollama (Local LLM)

  1. Download Ollama:
  • Visit Ollamas Website and download the installer for your operating system.
  1. Install and Run Ollama:
  • Follow the setup instructions to install.
  • Start Ollama and ensure it's running in the background.
  1. Connect to the Mod:
  • Use the gui to create/edit an NPC and put in the address to your ollama server (complete url with http://...;

if you're running your ollama on your local pc then you can just use the one that's already typed in)

Setup OpenAi (Paid)

  1. Create API Key
  1. Use the Key in the mod
  • Open the GUI and create an NPC with the LLM Type OPENAI and paste key into the Key field. (The key wont be ever shared with any other clients that has access to the GUI, also not your client. It will be saved in a secondbrain config file on the server)

Usage with Player2 App

>The mod will automatically sync the selected Characters from the player2 App to NPCs in your singleplayer world. If you updated a description/name in the player2 App you can sync these changes with the command /secondbrain player2 SYNC It's not possible to change any configs from the Character with this mod.

Interact with NPCs

  • Write messages in the chat or directly to a specific NPC
  • Press and hold alt (win) or opt (macOS) key to talk directly to the LLM/AI
  • Activate Text-To-Speech for any NPC in the config gui to hear the LLM/AI output

Setup Player2 (Free, Limited)

  1. Download Player2 App
  1. Start the App and select Characters
  • Start the downloaded App and select the Characters you wanna use as NPCs

License

This project is licensed under the LGPL-3.0

Disclaimer

Credits

This project utilizes components from the following projects:

Thank you to the developers of these projects for their amazing work!

Highlights

From source data

Game versions

Supports 8 Minecraft versions, the newest being 1.21.11.

Loaders

Runs on Fabric.

Footprint

Rated a light load on a server.

What kind of mod it is

From the catalog
Listed on Modrinth as “Mods”

Creatures & NPCs

Adds or changes creatures, NPCs and how they behave.

Runs on your server

From source side support

Modrinth lists SecondBrain as required on the server. Check its Modrinth page to see whether players need it too.

Compatibility

Game
Minecraft
Loaders
Fabric
Runs on
Serverrequired on the server
Game versions
1.21.11 and 7 earlier

Verified at the source

  • ✓ModrinthOfficial listing, checked 2026-10-01Open ↗
  • ✓Authorsailex, as published on Modrinth
  • ✓LicenseLGPL-3.0-onlyFree

SecondBrain, answered

Generated from the mod’s own source data.

Do my players need to install SecondBrain?

Modrinth lists SecondBrain as required on the server. Check its Modrinth page to see whether players need it too.

Which loaders does it support?

Fabric.

Is it free?

Yes. SecondBrain is free to download from Modrinth. Its license is LGPL-3.0-only.

How do I add it to my Nxeon server?

Use “Add to a server” on this page, or open NxLabs from your dashboard. We install it, restart your server and switch it on.

NxLabs

Run SecondBrain on a Minecraft server.

Deploy in about a minute from $4.20 a month, then add SecondBrain in one click.