{
  "markdown": "# MythxEngine — tabletop RPG engine over MCP\n\n[![CI](https://github.com/protoLabsAI/mythx-mcp/actions/workflows/ci.yml/badge.svg)](https://github.com/protoLabsAI/mythx-mcp/actions/workflows/ci.yml)\n[![npm](https://img.shields.io/npm/v/@mythxengine/mcp-server?label=npm)](https://www.npmjs.com/package/@mythxengine/mcp-server)\n[![license: MIT](https://img.shields.io/badge/license-MIT-blue.svg)](./LICENSE)\n[![node](https://img.shields.io/badge/node-%3E%3D22.13-brightgreen)](#install)\n\nA complete tabletop RPG engine your AI can run: deterministic dice, five-tier\noutcomes, FitD-style stress, combat tracking, situation clocks, investigations,\nNPC relationships, world generation — 134 tools over the\n[Model Context Protocol](https://modelcontextprotocol.io), with **four complete\nstarter worlds** bundled in.\n\nClaude (or any MCP client) becomes your Game Master. The engine keeps the\nrules honest: same seed + same actions = same outcome.\n\n## Install\n\n### Claude Code — plugin (skills + tools, recommended)\n\n```\n/plugin marketplace add protoLabsAI/mythx-mcp\n/plugin install rpg@mythx-plugins\n```\n\nOne install delivers the MCP server plus play skills (`/rpg:play`,\n`/rpg:combat-mode`, `/rpg:world-building-mode`, …).\n\n### Claude Code — tools only\n\n```bash\nclaude mcp add rpg -- npx -y @mythxengine/mcp-server\n```\n\nRequires Node >= 22.13.\n\n### Claude Desktop\n\nDownload `mythxengine-<version>.mcpb` from the\n[latest release](https://github.com/protoLabsAI/mythx-mcp/releases/latest) and\ndrag it into **Settings → Extensions**. No other setup — Claude Desktop ships\nits own Node runtime.\n\n## Five-minute walkthrough\n\nEverything below is one conversation with Claude after installing. Four worlds\nare imported on first run — Port Miriam (harbor noir), Aethelgard (mythic\nfrontier), Threshold Deep (weird depths), and the Treehouse Anthology.\n\n**1. Pick a world, make a character.**\n\n> Start a session in Port Miriam. I want to play a dockside fixer who owes the\n> wrong people money.\n\nThe GM calls `create_session`, `load_world_summary`, and `create_character` —\nyour fixer gets HP, stress, gear, and a spot in the world's faction web.\n\n**2. Roll with real stakes.** Every test is framed with position (how bad is\nfailure?) and effect (how much does success buy?):\n\n> I try to slip past the harbor patrol to reach the smuggler's skiff.\n\n```\nroll_test → risky position / standard effect → 11 vs 13: partial\n\"Yes, but...\" — you reach the skiff, and a lantern swings your way.\nGM move suggested: put_someone_in_spot\n```\n\nFive outcomes — critical success, success, partial, failure, critical\nfailure — and on a bad roll you can `push_roll` (spend 2 stress for +1d6) or\n`resist_consequence` to buy the severity down. Stress is a real currency;\noverflow means trauma.\n\n**3. Fight a combat round.**\n\n> Two dockhands block the gangway. I draw my hook-knife.\n\n`start_combat` → `roll_initiative` → `attack` — initiative order, armor,\nconditions, and damage all tracked; every attack returns the same five-tier\noutcome with suggested GM moves on a miss.\n\n**4. Watch a clock tick.** The patrol you dodged? The GM started a\n`harbor-alert` clock. Fail forward enough times (`tick_clock` fires\nautomatically on partials/failures when wired) and the dock lights come on —\nconsequences arrive on schedule, not by fiat.\n\nThat's the loop: fiction in, mechanics out, consequences on clocks.\n\n## What's in the box\n\n| Piece                                    | What it gives you                                                  |\n| ---------------------------------------- | ------------------------------------------------------------------ |\n| `packages/mcp-server`                    | The MCP server — 134 tools, published as `@mythxengine/mcp-server` |\n| `packages/engine`                        | Pure, seeded game mechanics (dice, outcomes, combat)               |\n| `packages/types` / `worlds` / `rulebook` | Zod-validated schemas for every entity, plus rules lookup          |\n| `packages/storage`                       | SQLite persistence (`node:sqlite`, zero native deps)               |\n| `packages/tools` / `prompts`             | Transport-agnostic tool implementations + runtime GM skills        |\n| `world-builder/`                         | The `rpg` Claude Code plugin (skills, agents, hooks)               |\n| `agent-kit/`                             | Portable GM system prompt + operating manual for **any** agent     |\n| `docs/`                                  | The [rulebook](./docs/RULEBOOK.md) + [how the engine works](./docs/engine.md) |\n| 4 bundled worlds                         | ~13 MB of NPCs, factions, locations, situations, arcs — the demo   |\n\n## Rules & docs\n\n- **[docs/RULEBOOK.md](./docs/RULEBOOK.md)** — the complete rules, all 12\n  chapters (outcomes, position & effect, tests, stress, combat, conditions,\n  gear, time & clocks, GM moves). Generated from `packages/rulebook`, the same\n  source the `lookup_rule` and `generate_rulebook` tools serve — so it never\n  drifts from the engine.\n- **[docs/engine.md](./docs/engine.md)** — how the engine works: the five-tier\n  outcome system, position & effect, stress, deterministic RNG, and how the\n  packages fit together.\n- **[agent-kit/](./agent-kit/)** — a portable GM system prompt and operating\n  manual for running a game with any agent.\n\n## Want the full experience?\n\nThis repo is the engine. **MythxEngine Desktop** is the game: a visual\nframe-based play surface, scene imagery, generated world books, and\npolish. Follow along and get notified when it ships at\n[mythxengine.com](https://mythxengine.com).\n\n## Development\n\n```bash\npnpm install\npnpm build && pnpm test && pnpm lint && pnpm typecheck\n```\n\nSee [CONTRIBUTING.md](./CONTRIBUTING.md) — this repo is a downstream mirror of\na private monorepo; issues are the fastest way to get fixes in.\n\n## License\n\n[MIT](./LICENSE) © protoLabs Studio\n",
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