Highly Performant & Scalable Ultima Online Server Emulator
https://www.modernuo.com
c-sharpcsharpcsharp-coredotnetdotnet-coreemulatorgplgplv3mmommo-enginemmorpgmmorpg-serveronlinerpgrunuoserverservuoultimaultima-onlineuo
Fixes #1690. Addresses Blood Oath holistically — three bugs found while researching the spell against RunUO, ServUO, the UODemise/uo.com guides, and the archived UOGuide page. ## Bugs fixed ### 1. Expiry timing (the filed issue) The `ExpireTimer` polled every 1s, so expiry and death/delete cleanup lagged up to ~1s. Replaced with a **single-shot** timer plus centralized `[OnEvent]` handlers on `PlayerDeathEvent`/`PlayerDeletedEvent`/`CreatureDeathEvent`/`CreatureDeletedEvent` — the oath now breaks immediately on death/delete of either party. ### 2. Duration formula Used `/80` (the bugged in-game tooltip value) instead of the real OSI formula `((SpiritSpeak - Resist) / 8) + 8`. Confirmed by RunUO, ServUO, the emulator guides, and the code's own fixed-point comment. At GM Spirit Speak this changes duration from ~9.5s to 23s and makes Spirit Speak actually affect duration. ### 3. Damage reflection (`BaseCreature.Damage` vs `PlayerMobile.Damage`) `BaseCreature.Damage` diverged: it attributed the reflected hit to the attacker itself (`from.Damage(amount, from)`) instead of the caster, reflected the bonused (not original) amount, used `×1.1` vs `×1.2`, lacked the caster-survival guard, and had no Publish 48 resist mitigation. Unified both paths: reflect the **original** damage attributed to the **caster** at `×1.2`. Publish 48 resist mitigation now applies only to creature casters and is gated behind `Core.SA`. ## Internals - Collapsed the parallel `_oathTable` into a single `_table` keyed by both participants → shared timer, so `RemoveCurse` resolves from either side (required by the event handlers). - Extracted `GetDurationSeconds` and `ComputeReflectedDamage` as testable statics. ## Tests 13 new tests (duration formula, reflection mitigation, oath lifecycle, end-to-end event-driven removal). Full suite: **436/436 pass**. |
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| Distribution/Data | ||
| Projects | ||
| .cursorrules | ||
| .editorconfig | ||
| .gitattributes | ||
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| AGENTS.md | ||
| azure-pipelines.yml | ||
| CLAUDE.md | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| Directory.Build.props | ||
| FAQ.md | ||
| GEMINI.md | ||
| global.json | ||
| LICENSE | ||
| ModernUO.slnx | ||
| publish.cmd | ||
| publish.ps1 | ||
| publish.sh | ||
| README.md | ||
| rider-settings.zip | ||
| Rules.ruleset | ||
| SPONSORS.md | ||
| stylecop.json | ||
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| 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
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, 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
- 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