CRYOGENIC

Reverse Engineering the Classic Dune Game

📚 GitHub Page

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Table of Contents

• About the Project
• Project Goals
• Technology - Spice86
• Status
• Prerequisites
• Build & Run
  • Building
  • Running (Basic Mode)
  • Running with Audio
• Screenshots
• Contributing
• Resources
• License

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About the Project

Cryogenic is an ambitious reverse engineering project dedicated to understanding and modernizing Cryo's Dune (CD Version, 1992) - one of the most atmospheric adventure games of the early 90s.

Using the powerful Spice86 reverse engineering toolkit, we're gradually rewriting the game from x86 assembly into readable, maintainable C# code. The game is fully playable right now, complete with sound and music support.

As we continue to replace assembly routines with C# implementations, the codebase becomes more accessible to modern developers while preserving the exact behavior of the original DOS executable.

Supported Version

SHA256 signature of supported DNCDPRG.EXE:

5f30aeb84d67cf2e053a83c09c2890f010f2e25ee877ebec58ea15c5b30cfff9

⚠️ Note: The CD release of DUNE (version 3.7, the most widely available one) must be obtained separately, as it is copyrighted material.

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Project Goals

🔍 Understand the Game - Deep dive into the inner workings of Dune's game engine, uncovering how Cryo implemented dialogue systems, resource management, and real-time strategy elements in the DOS era.

🔄 Incremental Rewriting - Gradually replace x86 assembly routines with clean, documented C# code while maintaining 100% behavioral compatibility with the original game.

📚 Document Everything - Create comprehensive documentation of game mechanics, data structures, and algorithms to preserve this knowledge for future developers and gaming historians.

🎮 Preserve Gaming History - Ensure this classic adventure game remains playable on modern systems and provide a foundation for potential future enhancements and ports.

🛠️ Educational Resource - Serve as a reference implementation for reverse engineering techniques and demonstrate the power of hybrid emulation approaches.

🌐 Cross-Platform Support - Leverage .NET 8's cross-platform capabilities to run the game natively on Windows, macOS, and Linux without emulation layers.

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Technology - Spice86

What is Spice86?

Spice86 is a revolutionary reverse engineering toolkit and PC emulator specifically designed for 16-bit real mode x86 programs. Unlike traditional emulators that simply run old software, Spice86 enables you to gradually modernize legacy DOS applications by replacing assembly code with high-level C# implementations.

Built on .NET 8, Spice86 provides a unique hybrid execution model where the original DOS executable runs alongside your C# overrides, allowing for incremental reverse engineering and testing.

Key Features

• 🔄 Hybrid Execution - Run original DOS binaries while selectively replacing functions with C# implementations. Test your reverse-engineered code against the real thing in real-time.
• 🔬 Runtime Analysis - Collect memory dumps, execution traces, and runtime data while the program runs.
• 🎯 Ghidra Integration - Import runtime data into Ghidra for static analysis.
• 🐛 Advanced Debugging - Built-in debugger with GDB remote protocol support.
• 🎮 Hardware Emulation - Complete support for VGA/EGA/CGA graphics, PC Speaker, AdLib, SoundBlaster, keyboard, and mouse.
• 🌍 Cross-Platform - Built on .NET 8 for Windows, macOS, and Linux.

How Cryogenic Uses Spice86

1. Override Registration - Cryogenic registers C# function overrides in DuneCdOverrideSupplier that replace specific assembly routines at runtime.
2. Segment Management - Memory segments (CS1=0x1000 for main code, CS2/3/4 for drivers, CS5=0xF000 for BIOS) are carefully managed.
3. Hybrid Execution - When DNCDPRG.EXE calls an overridden function, Spice86 redirects execution to the C# implementation.
4. State Synchronization - Global game state accessors like globalsOnDs ensure C# code and assembly share the same memory.

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Status

Thanks to the hybrid ASM / .NET mode provided by Spice86, the game is fully playable, including sound and music.

The goal is to have more and more logic written in human-readable C#, making the codebase accessible to modern developers while preserving the classic gameplay experience.

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Prerequisites

Before you begin, ensure you have:

1. .NET 8 SDK - Required to build and run the project
2. Dune CD Version 3.7 - You must obtain DNCDPRG.EXE and DUNE.DAT separately (copyrighted material)

You can verify your executable with PowerShell:

Get-FileHash DNCDPRG.EXE -Algorithm SHA256

Or on Linux/Mac:

sha256sum DNCDPRG.EXE

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Build & Run

Building

Clone the repository and build the project:

git clone https://github.com/OpenRakis/Cryogenic
cd Cryogenic/src
dotnet build

Running (Basic Mode)

Ensure that DUNE.DAT and DNCDPRG.EXE are in the same folder, then run:

cd Cryogenic/src
dotnet run --Exe C:/path/to/dunecd/DNCDPRG.EXE --UseCodeOverride true -p 4096

⚠️ Important: Always use --UseCodeOverride true or your C# code won't execute!

Running with Audio

For the full experience with AdLib music and PCM sound effects:

cd Cryogenic/src/Cryogenic
dotnet publish
bin/Release/net8.0/publish/Cryogenic --Exe C:/path/to/dunecd/DNCDPRG.EXE --UseCodeOverride true -p 4096 -a "ADL220 SBP2227"

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Screenshots

Encounter with the mighty sandworm

Meeting with Chani

Sending Spice to the Emperor

Harkonnen confrontation

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Contributing

We welcome contributions from developers of all skill levels! Whether you're experienced in reverse engineering or just getting started, there's a place for you in this project.

Ways to Contribute

• 🔍 Reverse Engineering - Analyze assembly code, identify functions, and create C# implementations
• 📝 Documentation - Help document game mechanics, data structures, and code functionality
• 🧪 Testing - Play the game, find bugs, and verify that C# overrides behave identically to the original
• 🛠️ Code Quality - Improve existing C# code, refactor for clarity, and add helpful comments

Getting Started

1. Fork the repository on GitHub
2. Clone your fork locally
3. Read the CONTRIBUTING.md file for detailed guidelines
4. Pick an issue labeled good first issue or help wanted
5. Create a feature branch for your work
6. Make your changes and test thoroughly
7. Submit a pull request

For detailed contribution guidelines, architecture notes, and coding conventions, please see our CONTRIBUTING.md file.

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Resources

• 🌐 Project Website - Comprehensive documentation
• 🐙 GitHub Repository - Source code, issues, and releases
• 🌶️ Spice86 Project - The reverse engineering toolkit powering Cryogenic
• 📦 Releases - Download the latest version
• 📖 Dune (1992) - Wikipedia - Learn about the original game

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License

Cryogenic is open-source software licensed under the Apache License 2.0.

© 2021-2024 Kevin Ferrare and contributors.

Dune is © Cryo Interactive Entertainment. This project is not affiliated with or endorsed by Cryo Interactive Entertainment or any rights holders.