u5d - Ultima V Decompilation Project

Introduction

This is an ongoing decompilation project of Ultima V: Warriors of Destiny.

Inspired by u4-decompiled, I started this project as a personal challenge to better understand the original game and its codebase.

Goals

• Create a functionally equivalent version of the original game that can run on modern platforms.

• Match as much of the original code (v1.16 for MS-DOS) as possible.

Since the original linker (an unknown version of PLINK86) has not been found, perfect binary matching is currently impossible. Instead, the project focuses on assembly-level semantic matching.

When necessary, disassemblies from other platforms such as FM-TOWNS are also used as references.

Current Status

Matching Progress

• ULTIMA.EXE: approximately 95% matched, excluding assembly functions
• *.OVL: approximately 95% matched

Playability

The game can be played through to the ending using the original data files. However, major and minor bugs may still remain throughout the game.

Building

Windows Target

Open u5win/u5win.slnx with Visual Studio 2026 and build the solution.

MS-DOS Target (DJGPP)

Run make on a machine with DJGPP installed.

Depending on the environment, you may need to adjust the CROSS_CC_PREFIX value in the Makefile.

MS-DOS Target (Original Toolchain)

Run src\build.bat on a machine or virtual machine with Microsoft C 5.1 installed.

The compiler installation path is C:\MSC51.

Note: executable linking is currently not possible. This target is used only for disassembly matching.

Credits

• Ultima Codex Wiki - for game data and save-file formats
• Exodus Project - for the annotated disassembly
• The original Ultima V was created by Origin Systems and Lord British.