What Is GUO

What is GUO?

GodotUO (GUO) is a game client for Classic Ultima Online, the program players run on their own machine to connect to a shard. It is not a server or an emulator: it doesn't replace RunUO, ServUO or ModernUO. It connects to them, just as the official client and ClassicUO do.

GUO is a port of ClassicUO (CUO) to the Godot 4 engine. ClassicUO's C# (its network code, file readers and game logic) is carried across as it is; only the parts that were tied to its old graphics framework (FNA) are rebuilt on Godot: drawing, input and sound. The first goal is to behave exactly like ClassicUO. New features come on top of that, and never at the cost of it.

You bring your own Ultima Online installation. GUO contains no game data and never writes to your install.

Is it a client or an emulator?

A client. Here's the split:

	What it is	Examples
Server / emulator	Runs the world: accounts, NPCs, items, combat rules	RunUO, ServUO, ModernUO, Sphere
Client	What the player runs to see and play that world	the official client, ClassicUO, GUO

GUO speaks the same network protocol as ClassicUO, so it works with the same shards. Day to day it's developed and tested against a local ModernUO shard; the editor also talks to ServUO.

How is it different from ClassicUO?

	ClassicUO	GUO
Engine	FNA (a reimplementation of XNA)	Godot 4 (.NET / C#)
Game code	the original	ClassicUO's, ported with every change marked and checked in CI
Windows, Linux, macOS desktop	yes	Windows now; Linux as the Steam Deck build
Android phones and handhelds	no	yes, with a full touch layer (see below)
Dual-screen handhelds (AYN Thor)	no	yes: the world on top, your windows on the bottom
Steam Deck	via Proton/Linux	native Linux build with its own deploy tools
In a web browser	no	yes, plays on a shard in Chrome (a community engine build; early)
Assistant plugins (Razor etc.)	yes	yes on Windows, through ClassicUO's plugin interface
Built-in world and art editor	no	yes, inside the Godot editor (see below)
Content packs / Asset Store	no	yes: backgrounds, screensavers, themes, sounds, layout presets
Licence	BSD 2-Clause	BSD 2-Clause (keeps ClassicUO's copyright)

On a desktop with a mouse, GUO aims to look and play exactly like ClassicUO. The mobile features below only switch on for touch screens.

What GUO adds

• Touch play: a touch bar, a combat macro row, Self/Cancel while targeting, finger-sized grid containers, pinch to resize any window, and hold-and-flick to move, close or reset a window.
• Two screens: on dual-screen handhelds your paperdoll, backpack, journal and status live on the lower screen, and you can send any window to either screen.
• The GodotUO editor: browse all the UO art, gumps, animations, hues and maps; view the real world; paint land, place statics and whole houses; import your own art and gumps as PNG; place spawners and decorations, and push them to a running shard live, with no restart. Edits are kept in a project on top of the map, never in your install, and export to ModernUO or ServUO.
• The Asset Store: a catalogue you can run yourself. The client installs, updates and removes packs, checking every file. It never accepts UO game data.
• Quality of life: a canvas background around the game, OLED screensavers, a boot splash, per-platform default settings, and downloadable builds for every platform from each change.

What it isn't (yet)

• Pre-release. It logs in, walks, trades, opens gumps and runs assistant plugins, but it's not yet pixel-identical to ClassicUO everywhere. Known Issues lists the gaps.
• Not a server. To play you need a shard (your own, or one you trust).
• No game data. Every build needs your own UO installation.

Where to go next

• Getting Started: install, point GUO at your UO folder, play.
• Known Issues: what's rough today.
• Web Client, Android Build, Steam Deck, Editor: one page per platform or tool.
• FAQ: short answers.

Ultima Online is a registered trademark of Electronic Arts Inc. GUO is an unofficial fan project, not affiliated with or endorsed by Electronic Arts or Broadsword Online Games.