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limbonaut/limboai

A C++ plugin for Godot 4 that adds behavior trees and hierarchical state machines for building game AI, with an editor and visual debugger.

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What is it?

LimboAI is a plugin for Godot Engine 4 that provides behavior trees and state machines, which can be combined to build complex agent behaviors such as characters and enemies. It includes a behavior tree editor, built-in class documentation, a visual debugger that inspects running trees, and a demo project with a tutorial.

Behavior trees are built from composite, decorator, condition and action tasks, and custom tasks can be written by extending the core classes in C++ or GDScript. A blackboard system shares data between tasks, with plans, scopes and exported parameters for reuse across agents. Hierarchical state machines use event-based transitions and can be nested, with BTState bridging the two systems.

The project can be used as a C++ engine module or as a GDExtension shared library, so custom engine builds are not required. State machines are configured in code, since there is no GUI editor for them.

Key features

  • 01Behavior tree editor for creating and saving BehaviorTree resources
  • 02Visual debugger for inspecting running behavior trees
  • 03Blackboard system with plans, scopes and exported parameters
  • 04Hierarchical state machines with event-based transitions
  • 05Custom tasks in C++ or GDScript

Use cases

  • Designing enemy or NPC AI in a Godot 4 game
  • Prototyping state-driven character logic quickly in a game jam
  • Organizing reusable AI behaviors across several agents

Quick start

  1. 1

    Download a precompiled build or the demo project from the Releases page

  2. 2

    Open demo/scenes/showcase.tscn in Godot to see the examples

  3. 3

    To build the GDExtension from source, you need SCons and a C++ compiler, then run the build

    scons target=editor

Things to know

  • The GDExtension version requires Godot 4.6 or higher and has somewhat fewer features than the C++ module.
  • State machine setup and initialization require code, since there is no GUI editor for them.

Topics

#godot-engine#behavior-tree#state-machine#game-ai#gdextension#game-development#artificial-intelligence#game-developement#godot4#state-machines

FAQ

What is limboai?
A C++ plugin for Godot 4 that adds behavior trees and hierarchical state machines for building game AI, with an editor and visual debugger. LimboAI is a plugin for Godot Engine 4 that provides behavior trees and state machines, which can be combined to build complex agent behaviors such as characters and enemies. It includes a behavior tree editor, built-in class documentation, a visual debugger that inspects running trees, and a demo project with a tutorial.
Is limboai free to use? What license does it have?
limboai is open source under the MIT license. Check the license terms before using it in commercial products.
Is limboai still maintained?
Actively maintained. The last commit to limboai was on Oct 4, 2026.
What can I use limboai for?
Designing enemy or NPC AI in a Godot 4 game Prototyping state-driven character logic quickly in a game jam Organizing reusable AI behaviors across several agents
How do I install limboai?
Download a precompiled build or the demo project from the Releases page Open demo/scenes/showcase.tscn in Godot to see the examples To build the GDExtension from source, you need SCons and a C++ compiler, then run the build: scons target=editor
Where can I get limboai?
The source code and installation instructions are on GitHub: https://github.com/limbonaut/limboai

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