Highly Performant & Scalable Ultima Online Server Emulator
https://www.modernuo.com
c-sharpcsharpcsharp-coredotnetdotnet-coreemulatorgplgplv3mmommo-enginemmorpgmmorpg-serveronlinerpgrunuoserverservuoultimaultima-onlineuo
Summary
- Adds CLAUDE.md at repo root with 14 terse code audit rules (always loaded, low token cost)
- Adds pointer files for other AI tools: AGENTS.md (Codex), GEMINI.md, .github/COPILOT-INSTRUCTIONS.md (Copilot), .cursorrules (Cursor) — all redirect to CLAUDE.md as single source of truth
- Gitignores /.claude so personal AI config isn't distributed
- Moves Claude skills to dev-docs/claude-skills/ (opt-in, not auto-loaded)
- Adds 14 dev-docs covering codebase conventions
Code Audit Rules (in CLAUDE.md)
1. LINQ tiered rules (Tier 1 free, Tier 2 warm, Tier 3 forbidden)
2. No Console.WriteLine — use LogFactory.GetLogger()
3. No concurrency primitives in game code
4. No World.Mobiles/World.Items iteration
5. Clean up refs in OnDelete()/OnAfterDelete()
6. Cancel timers in OnDelete()/OnAfterDelete()
7. STArrayPool<T>.Shared not ArrayPool<T>.Shared
8. PooledRefList<T> not new List<T>() on hot paths
9. Serialization: partial class, [Constructible], no serialized TimerExecutionToken
10. No Task.Run/new Thread() in game code
11. Never assume era — ask which expansion
12. _camelCase fields, PascalCase properties/methods
13. No empty gumps — use DisplayTo() pattern
14. PropertyList string literals must be {} holes, cliloc-as-argument uses :#
|
||
|---|---|---|
| .config | ||
| .github | ||
| dev-docs | ||
| Distribution/Data | ||
| docs | ||
| Projects | ||
| .cursorrules | ||
| .editorconfig | ||
| .gitattributes | ||
| .gitignore | ||
| AGENTS.md | ||
| azure-pipelines.yml | ||
| CLAUDE.md | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| Directory.Build.props | ||
| FAQ.md | ||
| GEMINI.md | ||
| global.json | ||
| LICENSE | ||
| mkdocs.yml | ||
| ModernUO.sln | ||
| publish.cmd | ||
| publish.sh | ||
| README.md | ||
| rider-settings.zip | ||
| Rules.ruleset | ||
| SPONSORS.md | ||
| stylecop.json | ||
| THIRD-PARTY-NOTICES | ||
| version.json | ||
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
- Run
./publish.cmd [release|debug (default: release)] [os] [arch (default: x64)]os- Supported operating systemsarchx64- Intel/AMD 64-bitarm64- ARM 64-bit (Windows not supported)
Linux Prerequisites
Fedora, CentOS, RHEL, etc
dnf upgrade --refresh -y
# CentOS does not come with EPEL enabled
dnf install -y epel-release epel-next-release
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
- Run
ModernUO.exeordotnet ModernUO.dllfrom theDistributiondirectory
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