# OUO: a reconstructed Ultima Online demo server

> OUO reconstructs the Ultima Online demo server from UoDemo.exe as a C99 program for POSIX systems. Its function-by-function workflow uses disassembly of the original executable, while added server systems and protocol changes support later Ultima Online clients.

- Type: Case study
- Targets: Game
- Category: Independent reconstruction cases
- Relationship: Independent reconstruction project
- Sources reviewed: 2026-11-06
- Added to the catalog: 2026-11-09
- Original resource: <https://github.com/draxinar/ouo>
- Primary source: <https://github.com/draxinar/ouo/blob/814ea87fad53b94268cb48d9b1af0e5fcfc6fc18/README.md>
- Catalog page: <https://awesomerea.org/resources/ouo-case/>
- Record JSON: <https://awesomerea.org/resources/ouo-case/record.json>
- Chinese version: [简体中文](https://awesomerea.org/zh/resources/ouo-case/index.md)

## Requirements & limits

- **Prerequisites:** A POSIX system with gcc, make and git, plus the separate rundir server data, is needed for the documented installation.
- **Testing evidence:** Ultima Online clients 1.25.30 through 5.0.9.1 are the documented tested range.
- **License:** The repository's C source is licensed under the MIT License; the original UoDemo files are excluded from that license.

## Primary sources

1. <https://github.com/draxinar/ouo/blob/814ea87fad53b94268cb48d9b1af0e5fcfc6fc18/README.md>
2. <https://github.com/draxinar/ouo/blob/814ea87fad53b94268cb48d9b1af0e5fcfc6fc18/USAGE.md>
3. <https://github.com/draxinar/ouo/blob/814ea87fad53b94268cb48d9b1af0e5fcfc6fc18/LICENSE>

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## About this entry

The description was reviewed against primary sources.
Original editorial content: MIT. Linked projects, papers and assets retain their own rights and licenses.