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HorizOn MCP Server

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Docs, live API tools and prompts for the horizOn game backend in Godot, Unity and Unreal.

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Docs, live API tools and prompts for the horizOn game backend in Godot, Unity and Unreal.

Security Report

2.5
Use Caution2.5Critical Risk

Valid MCP server (5 strong, 1 medium validity signals). 6 known CVEs in dependencies (2 critical, 3 high severity) Package registry verified. Imported from the Official MCP Registry.

6 files analyzed · 7 issues found

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What You'll Need

Set these up before or after installing:

horizOn project API key for the live API tools. The documentation works without it.Required

Environment variable: HORIZON_API_KEY

horizOn account key for the dashboard admin tools.Required

Environment variable: HORIZON_ACCOUNT_API_KEY

API base URL.Optional

Environment variable: HORIZON_BASE_URL

How to Install

Add this to your MCP configuration file:

{
  "mcpServers": {
    "io-github-projectmakersde-horizon-mcp": {
      "env": {
        "HORIZON_API_KEY": "your-horizon-api-key-here",
        "HORIZON_BASE_URL": "your-horizon-base-url-here",
        "HORIZON_ACCOUNT_API_KEY": "your-horizon-account-api-key-here"
      },
      "args": [
        "-y",
        "horizon-mcp"
      ],
      "command": "npx"
    }
  }
}

Documentation

View on GitHub

From the project's GitHub README.

horizOn MCP Server

npm version npm downloads License: MIT

MCP server for horizOn Backend-as-a-Service

Gives AI coding assistants documentation, live API tools, and workflow prompts for game and app development.


Quick Install

Add to your MCP client configuration (Claude Desktop, Cursor, etc.):

{
  "mcpServers": {
    "horizOn": {
      "command": "npx",
      "args": ["-y", "horizon-mcp"],
      "env": {
        "HORIZON_API_KEY": "your-api-key-here"
      }
    }
  }
}

Features

Resources (16 docs)

Documentation resources are served directly from the MCP server. No API key required.

URIDescription
horizon://overviewWhat is horizOn, core concepts (Account vs User), features, tier system, API structure, and SDKs
horizon://docs/authAuthentication methods (Anonymous, Email, Google), endpoints, SDK code examples, and common errors
horizon://docs/leaderboardLeaderboard score submission, top entries, user rank, entries around user, with SDK examples
horizon://docs/cloud-saveCloud save/load for JSON and binary data, tier size limits, SDK examples
horizon://docs/remote-configServer-side key-value configuration: feature flags, game balance, A/B testing. SDK examples
horizon://docs/localizationServer-side localized strings across 15 languages: per-key translations, single/all fetch, available languages. SDK examples
horizon://docs/newsIn-game news and announcements with language filtering. SDK examples
horizon://docs/gift-codesGift code validation and redemption for promotional rewards. SDK examples
horizon://docs/feedbackBug reports, feature requests, and general feedback submission. SDK examples
horizon://docs/user-logsServer-side event and error tracking. Requires BASIC tier or higher. SDK examples
horizon://docs/crash-reportingCrash report submission, session tracking, fingerprinting, breadcrumbs, and auto-regression detection. SDK examples
horizon://docs/email-sendingTransactional and event-based email delivery to registered users. Templates, scheduling, status tracking, and SMTP integration. SDK examples
horizon://api/referenceComplete API reference for all horizOn App API endpoints with request/response schemas
horizon://quickstart/godotStep-by-step guide to integrate horizOn in Godot with GDScript examples
horizon://quickstart/unityStep-by-step guide to integrate horizOn in Unity with C# examples
horizon://quickstart/unrealStep-by-step guide to integrate horizOn in Unreal Engine 5.5+ with the official horizOn SDK plugin. C++ and Blueprint examples

Tools (28 tools)

Live API tools that call the horizOn backend. Requires a valid API key.

horizon_submit_score, horizon_save_cloud_data and horizon_load_cloud_data also need the player's session: sign in first and pass the returned accessToken as sessionToken.

ToolDescription
horizon_test_connectionTest connection to the horizOn API (health check)
horizon_signup_anonymousCreate a new anonymous user account
horizon_signup_emailCreate a new user account with email and password
horizon_signin_emailSign in with email and password
horizon_signin_anonymousSign in with an anonymous token
horizon_check_authCheck whether a user session is still valid
horizon_list_leaderboardsList available leaderboard boards for multi-board calls
horizon_submit_scoreSubmit a score to the leaderboard
horizon_get_leaderboard_topGet the top leaderboard entries, optionally by board key
horizon_get_user_rankGet a user's leaderboard rank, optionally by board key
horizon_get_leaderboard_aroundGet leaderboard entries around a user's position, optionally by board key
horizon_save_cloud_dataSave cloud data for a user
horizon_load_cloud_dataLoad cloud save data for a user
horizon_get_remote_configGet a single remote config value by key
horizon_get_all_remote_configsGet all remote config values
horizon_get_localizationGet a single localized string by key, optionally for a specific language
horizon_get_all_localizationsGet all localized strings, optionally for a specific language
horizon_get_localization_languagesList the languages that have localizations for the app
horizon_get_newsGet news articles with optional language filtering
horizon_validate_gift_codeValidate a gift code without redeeming it
horizon_redeem_gift_codeRedeem a gift code for a user
horizon_submit_feedbackSubmit user feedback (bug reports, feature requests)
horizon_create_logCreate a server-side log entry (INFO, WARN, ERROR)
horizon_create_crash_reportSubmit a crash report (grouped by fingerprint, with regression detection)
horizon_create_crash_sessionRegister a game session for the crash-free rate
horizon_send_emailSend a transactional email to a registered user from a template
horizon_cancel_emailCancel a pending or scheduled email
horizon_get_email_statusGet the status of a sent or scheduled email

Prompts (4 prompts)

Workflow prompts that guide AI assistants through common horizOn tasks.

PromptDescription
integrate-featureGenerate integration code for a specific horizOn feature in your game engine
setup-authStep-by-step guide to set up horizOn authentication in your project
debug-connectionDiagnose and fix horizOn connection issues
explain-featureGet a detailed explanation of any horizOn feature

Configuration

VariableRequiredDescription
HORIZON_API_KEYYes (for tools)Your horizOn API key. Get one at horizon.pm
HORIZON_BASE_URLNoAPI base URL. Defaults to https://horizon.pm

Resources (documentation) work without an API key. Only the live API tools require authentication.

Admin Tools (v1.2+)

With an Account Key (creatable in your horizOn Dashboard -> API Keys -> Create -> Account Key), the MCP server exposes additional tools that let Claude manage your dashboard -- projects, remote config, news, email templates, gift codes, users, leaderboards, cloud-save data, crash reports, feedback, user logs, and SMTP.

How to get your Account Key

  1. Log in to your horizOn Dashboard
  2. Navigate to API Keys in the sidebar
  3. Click Create API Key
  4. Select Account Key as the key type
  5. Choose whether the key can access the entire account, a single Project API Key, or selected feature groups
  6. Click Create -- your key will be shown once. Copy it immediately.
  7. Add the key to your MCP configuration (see Setup below)

Setup

Add both keys to your MCP client configuration:

{
  "mcpServers": {
    "horizOn": {
      "command": "npx",
      "args": ["-y", "horizon-mcp"],
      "env": {
        "HORIZON_API_KEY": "your-project-key (for player-facing tools)",
        "HORIZON_ACCOUNT_API_KEY": "your-account-key (for dashboard tools)"
      }
    }
  }
}

Both can be set together or individually. Admin tools only register when the account key is set -- otherwise the server exposes only the original player-facing tools.

Scope

Account Keys inherit your account's tier (FREE/BASIC/PRO/ENTERPRISE) -- they grant no extra privileges. A key can be full-account, limited to a single Project API Key, limited to selected feature groups, or both. Platform-admin-only endpoints (Blog, Banner, System-Config) are automatically unreachable. A handful of ultra-sensitive endpoints (account deletion, credentials change, key management itself, subscription cancel) require a dashboard session and cannot be called via an Account Key.

When a key is project-scoped, the backend enforces that scope on direct HTTP calls too. Account-wide endpoints or ID-only endpoints that cannot prove project context are rejected for project-scoped keys.

Tool Groups

PrefixDescription
horizon_admin_projects_*Project API key management (create/update/regenerate/revoke/delete)
horizon_admin_remoteconfig_*Remote config CRUD
horizon_admin_news_*Multilingual news (titles/messages as {lang: content})
horizon_admin_emailtemplates_*Multilingual email templates with variables
horizon_admin_giftcodes_*Gift code CRUD + revoke
horizon_admin_users_*User management + statistics (no full-list needed)
horizon_admin_leaderboard_*Leaderboard entries + statistics
horizon_admin_cloudsave_*Cloud save data + statistics
horizon_admin_crashes_*Crash groups, reports, statistics
horizon_admin_feedback_*Read user feedback
horizon_admin_userlogs_*Read user logs
horizon_admin_smtp_*Account SMTP configuration (password always returned masked)

What is horizOn?

horizOn is a multi-tenant Backend-as-a-Service platform built for game and app developers. It provides a managed backend so developers can focus on building their game or app instead of server infrastructure.

Core features:

  • Authentication (Anonymous, Email, Google, Apple)
  • Leaderboards
  • Cloud Save
  • Remote Config
  • Localization
  • News and Announcements
  • Gift Codes
  • User Feedback
  • User Logs
  • Crash Reporting
  • Email Sending

Learn more at horizon.pm. Install this MCP server via npm.

Supported Engines

  • Godot 4.5+ -- GDScript SDK
  • Unity 6 -- C# SDK
  • Unreal Engine 5.5+ -- C++ and Blueprint SDK

Development

# Clone the repository
git clone https://github.com/ProjectMakersDE/horizOn-mcp.git
cd horizOn-mcp

# Install dependencies
npm install

# Start the server (development mode)
npm run dev

# Build for production
npm run build

# Run tests
npm test

License

MIT

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