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+# The Realm Online: Engine & Protocol Documentation
+
+## 1. Game Engine: Sierra Creative Interpreter (SCI) 2.1
+The Realm Online was developed using a heavily modified version of the **SCI 2.1** engine. 
+
+### Key Modifications:
+- **Networking Stack**: Unlike standard single-player SCI games (e.g., King's Quest), Realm includes a proprietary networking layer for real-time multiplayer interactions.
+- **Resource Management**: Uses `.res` and `.pqc` (Packaged Quest Content) files for storing tiles, sprites, and sounds.
+- **Client Logic**: Much of the client logic is written in SCI script (a Smalltalk-like language), but the core engine handles the rendering and networking primitives.
+
+### Tools for Asset Extraction:
+- **SCI Companion**: A modern tool for editing and viewing SCI resources.
+- **QuickBMS**: Can be used with custom scripts to extract files from `.pqc` archives.
+- **SCI Resource Viewer**: Useful for browsing sprites and tiles.
+
+## 2. Network Protocol
+The game uses a client-server architecture with multiple dedicated TCP ports for different services.
+
+### Port Mapping:
+- **6002 (Realm Server)**: Main game world communication.
+- **6003 (Auth Server)**: Login and authentication.
+- **6005 (Patch Server)**: Version checking and file updates.
+- **7002 (Route Server)**: Redirects clients to specific game instances/realms.
+- **8001 (Game Server)**: Individual game instance handling.
+
+### Handshake & Packet Structure:
+Based on community reverse-engineering (e.g., the `server_poc.py` script):
+- **Framework**: Many modern emulators use the **Twisted** framework (Python) to handle the asynchronous networking required.
+- **Packet Headers**: Packets typically have a size header followed by the payload.
+- **Authentication**: Involves a multi-step handshake where the client identifies itself, sends credentials, and receives a session token or redirection to a game server.
+
+## 3. Database Schema
+The community-maintained database (TRO-DB) provides schemas for the following:
+- **Mobs/NPCs**: Statistics, drops, and spawn logic.
+- **Items**: Equipment stats, consumable effects, and shop prices.
+- **Spells**: Damage formulas, mana costs, and requirements.
+- **Maps**: Area definitions, warp points, and shop inventory mappings.