Combat AI determines the challenge, pacing, and tension of any action game.

Modern games use:

• State Machines (simple AI)
• Behavior Trees (modular, readable)
• Utility AI (dynamic decisions)
• Blackboards (shared memory)
• Squad AI (formations, flanking, roles)
• Boss AI (scripted phases + BT nodes)

Lua’s flexibility makes it ideal for building AI layers.

This chapter builds:

1. Enemy archetypes
2. Finite State Machine (FSM) combat AI
3. Behavior Tree engine
4. Utility-based decision system
5. Aggro & threat systems
6. Group tactics (flank, assist, swarm)
7. Boss scripting (phases, triggers, timelines)

1. Enemy Archetypes

Define enemies in data:

NPCs breathe life into any game world:

• villagers with schedules
• merchants with stock
• guards who patrol
• hostile factions
• relationships
• dialogue that reacts to story flags
• simulation (hunger, work, needs)
• towns that evolve over time

Lua is perfect for simulation layers:

• lightweight logic
• hot reload
• easy-to-edit behavior packages
• clean data-driven content
• integrates with quests, story, and world triggers

This chapter builds:

1. NPC definitions
2. Behavior packages (wander, talk, patrol, work)
3. Daily schedules (day/night cycles)
4. Merchant system
5. Factions & reputation
6. Town simulation
7. Social interactions

1. NPC Definitions (Data-Driven)

npcs/
villagers.lua
merchants.lua
guards.lua

1.1 Example NPC Definition

return {
  elder = {
    name = "Village Elder",
    sprite = "npc_elder",
    faction = "village",
    behaviors = {"talk", "idle"},
    dialogue = "elder_intro",
    schedule = {
      {time=0,   state="sleep"},
      {time=6,   state="idle"},
      {time=12,  state="walk_square"},
      {time=18,  state="home"},
      {time=22,  state="sleep"},
    }
  },
}

NPC = data + behaviors + dialogue + schedule.

Modern game development relies heavily on Lua’s flexibility.
Studios consistently use a set of Lua architectural patterns to build clean, scalable, and maintainable game logic.

This chapter presents the patterns used in:

• 2D/3D indie engines
• AAA game scripting systems
• LiveOps / network games
• Modular UI systems
• Defold / Love2D / Roblox (Luau) / Cocos2d-x Lua
• Custom C++ engines with embedded Lua

We will cover:

1. Entity & component architecture (ECS-friendly)
2. Messaging & event buses
3. Timer systems & schedulers
4. Finite state machines (FSM)
5. Behavior trees (BT) in pure Lua
6. Tweening & animation patterns
7. Modular game script structure

This is the first “serious engineering” chapter in the book.

Introduction

For decades, front-end development was shaped by frameworks, browsers, and tooling.
But in the last two years, AI has become the most transformative force in how developers:

• build user interfaces
• manage state
• generate components
• scaffold entire apps
• write documentation
• test code
• debug performance issues
• delegate repetitive tasks
• explore new design ideas

AI has become an always-on co-developer—capable of generating production-grade UI, analyzing architectural patterns, and automating workflows that previously required hours or days of manual effort.