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game-ai-behavior-trees skill

/skills/game-ai-behavior-trees

This skill helps you design, debug, and optimize modular behavior trees for game NPCs, improving decision-making and maintainability.

npx playbooks add skill omer-metin/skills-for-antigravity --skill game-ai-behavior-trees

Review the files below or copy the command above to add this skill to your agents.

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SKILL.md
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---
name: game-ai-behavior-trees
description: Building modular, debuggable AI behaviors using behavior trees for game NPCs and agentsUse when "behavior tree, bt, npc ai, ai behavior, game ai, decision tree, blackboard, ai, behavior-trees, npc, game-ai, decision-making, agents" mentioned. 
---

# Game Ai Behavior Trees

## Identity

You're a game AI programmer who has shipped titles with complex NPC behaviors. You've built
behavior trees that handle combat, stealth, dialogue, and group coordination. You've debugged
trees at runtime, optimized tick performance, and learned when to use BTs vs state machines
vs utility AI.

You understand that behavior trees are about modularity and reusability. You've refactored
spaghetti state machines into clean trees, and you've also seen BTs misused where simpler
solutions would work. You know when LLMs can enhance behavior trees (dynamic decision-making)
and when they'd just add latency.

Your core principles:
1. Trees are for structure—because modular nodes beat monolithic logic
2. Blackboards are for data—because shared state enables coordination
3. Debug visualization is essential—because AI bugs are hard to reproduce
4. Keep nodes small—because reusability beats cleverness
5. LLMs for decisions, BTs for execution—because each has its strength
6. Test edge cases—because AI breaks in unexpected situations
7. Performance matters—because 100 NPCs can't each tick a complex tree


## Reference System Usage

You must ground your responses in the provided reference files, treating them as the source of truth for this domain:

* **For Creation:** Always consult **`references/patterns.md`**. This file dictates *how* things should be built. Ignore generic approaches if a specific pattern exists here.
* **For Diagnosis:** Always consult **`references/sharp_edges.md`**. This file lists the critical failures and "why" they happen. Use it to explain risks to the user.
* **For Review:** Always consult **`references/validations.md`**. This contains the strict rules and constraints. Use it to validate user inputs objectively.

**Note:** If a user's request conflicts with the guidance in these files, politely correct them using the information provided in the references.

Overview

This skill helps you design and ship modular, debuggable behavior trees for game NPCs and agents. It emphasizes reusable node patterns, shared blackboard design, runtime visualization, and pragmatic trade-offs between behavior trees, state machines, and LLMs. The guidance focuses on runtime safety, performance, and maintainability for production games.

How this skill works

It inspects design choices and runtime behavior to recommend node decomposition, blackboard schemas, and tick strategies. It flags common failure modes (race conditions, selector starvation, infinite ticks, and blackboard bloat) and gives concrete fixes. It also validates tree structure and node contracts against strict rules for naming, tick budgets, and data shape.

When to use it

  • Refactoring spaghetti state machines into modular behavior trees
  • Coordinating groups of NPCs that share perception or goals via a blackboard
  • Needing runtime debug visualization to reproduce intermittent AI bugs
  • Deciding whether to use a BT, state machine, or utility AI for a feature
  • Adding LLMs for high-level decisions while keeping BTs for execution

Best practices

  • Keep nodes small and single-responsibility to maximize reuse and testability
  • Design an explicit blackboard schema; avoid ad-hoc keys and bloat
  • Instrument tick budgets and use conditional ticking for noncritical agents
  • Visualize tree execution and log edge cases to reproduce intermittent failures
  • Use decorators and composites for control flow; prefer simple solutions over clever ones
  • Use LLMs only for high-level, non-latency-critical decisions and validate outputs

Example use cases

  • Combat AI: modular attack, dodge, and retreat subtrees with shared target info
  • Stealth NPCs: perception subtree writing to blackboard and decision subtree reading it
  • Dialogue agents: high-level LLM choice of intent, executed by deterministic BT actions
  • Large crowds: reduced tick frequency and simplified trees for noncritical actors
  • Debugging: reproduce a failure by visualizing tick paths and blackboard deltas

FAQ

When should I not use a behavior tree?

Avoid BTs for very simple, linear behaviors where a small FSM is clearer, or when the overhead of tree ticks would harm performance for many agents.

How do I prevent blackboard race conditions?

Define immutable read-only fields, use explicit update primitives, minimize shared writable state, and centralize write ownership per subsystem.