Highly Performant & Scalable Ultima Online Server Emulator
https://www.modernuo.com
c-sharpcsharpcsharp-coredotnetdotnet-coreemulatorgplgplv3mmommo-enginemmorpgmmorpg-serveronlinerpgrunuoserverservuoultimaultima-onlineuo
36e09bae13
## Summary - Fixes pets falling behind mounted masters in AOS+ by setting `CurrentSpeed = 0.1` when following master - Fixes AI timer permanently stopping when `Obey()`/`Think()` returns `false` for transient conditions - Fixes controlled pets losing AI in inactive sectors (pet follows owner across sector boundary, sector deactivates, AI dies) - Adds defense-in-depth: AI timer restarts on pet resurrection and order changes ## AI Timer Permanent Stop (Bug Fix) `AITimer.OnTick()` called `Stop()` when `Obey()` or `Think()` returned `false`. By that point, `ShouldStop()` had already validated the creature is alive, on a valid map, and in an active sector — so any `false` return was a **transient** condition, not terminal. The timer stopped permanently with no mechanism to restart it. **Scenarios that triggered permanent AI death:** - Dead bonded pet with attack order (`DoOrderAttack` returned `false` for `IsDeadPet`) - Failed pet transfer — loyalty refusal, combat, disconnected player, or pending trade (`DoOrderTransfer` returned `false` for 5 different transient conditions) - Unknown `OrderType` or `ActionType` (defensive defaults) **Fixes:** - Removed `Stop()` from the `Obey()`/`Think()` failure path — timer skips the tick and fires again next interval - Changed `DoOrderAttack()` and all five `DoOrderTransfer()` failure paths to return `true` (correct semantics: these are recoverable states, not "stop AI forever" signals) - Added `Activate()` call in `ResurrectPet()` — ensures dead bonded pets have AI running after resurrection - Added `Activate()` call in `OnCurrentOrderChanged()` — self-heals timer if any voice command is issued to a pet with a stopped timer ## Controlled Pet Sector Deactivation (Bug Fix) `ShouldStop()` stopped the AI timer for **all** `PlayerRangeSensitive` creatures in inactive sectors, including controlled pets. But `Deactivate()` intentionally exempted controlled pets. The exemption was dead code — `ShouldStop()` bypassed it. This matters when a pet follows its owner across a sector boundary: the owner enters the next sector (active), the pet's old sector deactivates (no more players), and the pet's AI dies. The pet stops following and stands there until the player backtracks far enough to reactivate the sector. **Fix:** Added `Controlled` check to `ShouldStop()` to match `Deactivate()`. Controlled pets now keep their AI running in inactive sectors. The overhead is negligible — controlled pets are bounded by follower slots. ## Movement Speed Simplification - Simplifies `AITimer` to use `CurrentSpeed` directly as the tick interval (in seconds), removing the complex multiplier/floor logic in `GetBaseInterval` - Refactors `DoMoveImpl` speed assignment into explicit if/else for clarity - AOS+ pets following master use `CurrentSpeed = 0.1` (100ms), matching `RunMountDelay` ## Files Changed - `AITimer.cs` — removed `Stop()` on Obey/Think failure, added `Controlled` exemption to `ShouldStop()`, simplified interval logic - `BaseAI.cs` — renamed `_timer` to `AITimer` (public), simplified `Deactivate()`, fixed `ReturnToHome` to use `Activate()` - `PetOrders.cs` — `DoOrderAttack` and `DoOrderTransfer` return `true` for transient failures - `PetOrderHandlers.cs` — `OnCurrentOrderChanged()` calls `Activate()` to self-heal stopped timers - `BaseCreature.cs` — `ResurrectPet()` calls `Activate()`, fixed `GoHome_Callback` PlayerRangeSensitive check - `AIMovement.cs` — refactored speed assignment, AOS+ follow-master speed fix |
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| Distribution/Data | ||
| 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 | ||
| ModernUO.slnx | ||
| publish.cmd | ||
| publish.ps1 | ||
| 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
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
