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GodotUO (GUO)

GodotUO ports the Classic Ultima Online client to Godot 4.7 .NET. It is a transplant of ClassicUO, not a rewrite: the network stack, the file readers and the game logic are carried across as C#, and only the parts that genuinely bind to FNA (the renderer, the input layer, the audio and the game loop) are reimplemented on Godot.

You supply your own Ultima Online installation. No game data is distributed with the project, and the client only ever reads your install.

Status in one screen

Release state	Pre-release. Playable on a local shard; not yet at pixel parity with ClassicUO.
Port coverage	396 / 396 upstream files present, by the audit's count (docs/port_status.md). "Ported" means present and compiling, not proven working.
What is verified	Logs in, walks, opens gumps and hosts assistant plugins against a local ModernUO shard (launchers\dev\playtest.bat, plugin_probe.bat). Side-by-side sweeps against ClassicUO in eight places: docs/parity_2026-09-23.md, docs/parity_2026-09-26_night.md.
Platforms	Windows 10/11 x64 (developed and exported). Android 12+ ARM64 debug APK, run on one device (ADR-0017). Steam Deck (SteamOS, Linux x86_64) export (ADR-0018). Web: plays on a local shard in Chrome (Firefox to the login screen) on a community engine build, see Web Client.
Engine	Godot 4.7.2 stable, mono/.NET build, pinned and fetched by the bootstrap step. The non-mono build will not work.
Language	C# on net8.0 (net9.0 for the Android export), Python 3.12 tooling.

Where to go

• New here: Getting Started, then Configuration.
• Want a build: Windows Build, Android Build, Steam Deck, Web Client, Dual Screen, or Download a build.
• Playing: Servers and Accounts, Controller, Asset Store.
• Playing on a phone: Mobile UI, Canvas Background.
• Something wrong: Troubleshooting, Known Issues, Community and Support.
• Building content: Building Multis, Author UO Data.
• Contributing: Contributing, Working with AI Agents, Roadmap, Glossary.
• A different look for the world: Screen Effects.
• Planning player helpers: Player command index and controller research.
• Planning the second screen: OpenMW-DS comparison, tabs, gump transfer, and pinch scaling.
• Resizing or moving windows: Gump size and screen controls.
• Need a server: Dev Shard.
• Working on the port: Launchers and Tools, Scripted Runs and Probes, Parity and Drift, Architecture, Editor, Manage Your Shard From the Editor, Author UO Data, Contributing.
• New to GUO: What is GUO?, and how it differs from ClassicUO.
• Short answers: FAQ.
• What does not work yet: Known Issues.

Licence

GUO is BSD 2-Clause, the same licence as ClassicUO. Ported files keep their upstream copyright header; the licence text and the reviewed upstream commit are in docs/upstream/. The .claude/ agents and skills are MIT, adapted from Claude Code Game Studios. Godot is MIT and is fetched, not redistributed.

Ultima Online is a registered trademark of Electronic Arts Inc. GUO is an unofficial, fan-made project with no affiliation to Electronic Arts or Broadsword Online Games, and it contains none of their game data.

How this wiki is kept honest

Every "works" statement on these pages traces to one of three things: an ADR's Validation section (docs/architecture/), a tool README's run log (tools/*/README.md, the "what has actually been run" tables), or a commit message that names the evidence. Where the sources themselves say a thing is written but not exercised, the page says written, not verified.