MythX RPG Plugin for Claude Code

Interactive tabletop RPG gameplay powered by the MythX Engine. Create worlds, build characters, and play adventures—all within Claude Code.

Installation

claude plugins install @mythxengine/claude-plugin

This will:

1. Install the plugin with skills and commands
2. Configure the MythX MCP server to start when you use /play

Quick Start

# Start Claude Code
claude

# Begin playing
/play

The /play command guides you through:

• Session Selection: Resume an existing game or start fresh
• World Creation: Choose a genre or describe your own world concept
• Character Creation: Pick from generated archetypes
• Gameplay: Full GM-driven adventure with dice mechanics

Commands

| Command | Description | |---------|-------------| | /play | Start or resume an RPG adventure | | /augment-world | Add new content to an existing world pack |

Game Flow

/play
   ↓
┌─────────────────────────────────┐
│  Session Selection              │
│  • Resume: <existing-game>      │
│  • Start New Game               │
└─────────────────────────────────┘
   ↓ (if new)
┌─────────────────────────────────┐
│  World Generation               │
│  7 parallel content generators  │
│  create archetypes, monsters,   │
│  items, locations, NPCs...      │
└─────────────────────────────────┘
   ↓
┌─────────────────────────────────┐
│  Character Creation             │
│  Choose from generated          │
│  archetypes, name your hero     │
└─────────────────────────────────┘
   ↓
┌─────────────────────────────────┐
│  Gameplay Loop                  │
│  GM narrates scenes             │
│  You decide actions             │
│  Dice determine outcomes        │
└─────────────────────────────────┘

Features

World Generation

• Procedural world creation from text prompts
• 7 parallel content generators for fast world building
• Archetypes, monsters, items, encounters, locations, NPCs, narrative hooks

Gameplay

• Full dice mechanics (d20 tests, damage rolls)
• Turn-based combat with initiative
• Character progression (HP, conditions, gear)
• Session persistence—resume any time

AI Companions

• Optional AI-controlled party members
• Configurable playstyles (tactical, roleplay, cautious, reckless)
• Authentic in-character decision making

GM Tools

• Research agents for quick lookups
• NPC expansion and roleplay skills
• Situation generator for rich scenes
• Deep roleplay for pivotal moments

Data Storage

Game sessions are stored in ~/.mythx/ by default. This persists across Claude Code sessions.

To use a custom location, set the environment variable:

export RPG_MCP_DATA_DIR=/path/to/your/data

Architecture

The plugin includes:

@mythxengine/claude-plugin/
├── .claude-plugin/
│   └── plugin.json          # Plugin manifest with MCP server config
├── commands/
│   ├── play.md              # Main /play command
│   └── augment-world.md     # World augmentation command
├── skills/
│   ├── play/SKILL.md        # Detailed gameplay skill
│   ├── npc-expansion.md     # NPC detail expansion
│   ├── roleplay-npc.md      # Quick NPC dialogue
│   └── situation-generator.md
└── agents/
    ├── content-generator.md # Parallel world generation
    ├── ai-player.md         # AI companion decision-making
    ├── gm-researcher.md     # GM research (full access)
    ├── player-researcher.md # Player research (no spoilers)
    └── deep-roleplay.md     # Method acting for pivotal moments

The MCP server (@mythxengine/mcp-server) provides 75+ tools for:

• Dice rolling and skill tests
• Character management
• Combat tracking
• Session persistence
• World generation
• GM runtime support

Requirements

• Claude Code with plugin support
• Node.js 18+ (for MCP server via npx)

Related Packages

• @mythxengine/mcp-server - The MCP server with all game mechanics
• @mythxengine/types - TypeScript types for the engine
• @mythxengine/engine - Pure game mechanics library

License

MIT