Highly Performant & Scalable Ultima Online Server Emulator
https://www.modernuo.com
c-sharpcsharpcsharp-coredotnetdotnet-coreemulatorgplgplv3mmommo-enginemmorpgmmorpg-serveronlinerpgrunuoserverservuoultimaultima-onlineuo
Two stalls hit CI in one night with nothing bounding them but the 360-minute default: a deadlocked test host (silent for 2h41m) and a stalled EPEL mirror mid-download in the dnf step (probing the pool showed the first mirror in the current US mirrorlist returning HTTP 500 and sibling mirrors serving mismatched metadata generations). - timeout-minutes: 30 on both jobs. Verified live: the cap killed a stalled job at exactly 30:02. - dotnet test --blame-hang-timeout 10m: a stuck test host is killed and the in-flight tests are named with a full process dump, instead of hanging until the job timeout. Test results (and dumps) upload as artifacts on failure. - EPEL setup follows the EPEL quickstart ordering: dnf-plugins-core, enable CRB, then epel-release. epel-next is not installed: none of the prerequisites need it, EPEL 10 does not have it, and it is one more mirrorlist to fetch. - Matrix: add Ubuntu 26.04 LTS, CentOS Stream 10, and AlmaLinux 10; bump Fedora 42 (EOL) to 44. README badges and Linux prerequisites updated to match. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> |
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| AGENTS.md | ||
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| FAQ.md | ||
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| LICENSE | ||
| ModernUO.slnx | ||
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| publish.sh | ||
| README.md | ||
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| SPONSORS.md | ||
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ModernUO

Ultima Online Server Emulator for the modern era!
Requirements
Supported Operating Systems
Required Frameworks
All Operating Systems
Windows
Development
Supported IDEs
Getting Started
- Install prerequisite requirements
- Clone this repository (or download the latest):
git clone https://github.com/modernuo/ModernUO.git
- Open
ModernUO.slnto start developing
Building/Publishing
Interactive Mode (Recommended for new users)
Run ./publish.cmd (Windows) or ./publish.sh (Linux/macOS) with no arguments to launch the guided build tool. It will:
- Check prerequisites (.NET SDK, native libraries)
- Walk you through configuration and platform selection
- Build and publish the server to the
Distributiondirectory - Show deployment instructions for cross-compiled builds
Command Line
./publish.cmd [release|debug] [os] [arch]
os- Supported operating systemsarchx64- Intel/AMD 64-bitarm64- ARM 64-bit
Linux Prerequisites
Fedora, CentOS, RHEL, AlmaLinux, Rocky, etc
dnf upgrade --refresh -y
# RHEL-family distributions (CentOS Stream, AlmaLinux, Rocky, RHEL) need CRB and EPEL enabled.
# Fedora skips this block.
dnf install -y dnf-plugins-core
dnf config-manager --set-enabled crb
dnf install -y epel-release
# Prerequisites
dnf install -y findutils libicu libdeflate-devel zstd libargon2-devel liburing-devel
Ubuntu, Debian, etc
apt-get update -y
apt-get install -y libicu-dev libdeflate-dev zstd libargon2-dev liburing-dev
OSX Requirements
brew install icu4c libdeflate zstd argon2
Running the Server
- Follow the publish instructions
- The
Distributiondirectory is portable — copy it to your production server for deployment - Run
ModernUO.exeordotnet ModernUO.dllfrom theDistributiondirectory - On first run, the server will prompt you to configure game data file locations
Troubleshooting / FAQ
- See FAQ
Want to sponsor?
Thank you for supporting us! You can find out how by visiting the sponsors page.
Collaborators
Thanks
- RunUO Team & Community
- Voxpire, the ServUO Team & Community
- Karasho, Jaedan and the ClassicUO Community
Development Tools & Plugins provided with ♥ by
Code Signing Policy
Free code signing provided by SignPath.io, certificate by SignPath Foundation.
This program will not transfer any information to other networked systems unless specifically requested by the user or the person installing or operating it
Teams & Roles
Approvers & Committers: Development Team