In its initial incarnation, Shattered Moon built this promising project in order to do for Ultima 4 what Ultima 6 Online had done for Ultima 6: rework a classic Ultima title to be playable online. He built both the game client and server which, when paired with the Ultima 4 game files on your hard drive (a free copy of Ultima 4 can be obtained via GOG), allowed you to take on the Quest of the Avatar…with your friends. Or with complete strangers!

Sadly, the only public server was taken offline toward the end of 2016. Concurrent with this, Shattered Moon reworked both the client and server for the game to allow for local, offline play, so the experience of Classic Ultima Online was not lost entirely…but further development on the project ceased for a time.

As of mid-2025, Shattered Moon briefly resumed working on the project, and expanded its support to include the first three Ultima games, as well as a plethora of additional official and fan-made tilesets. However, as of this week (not coincidentally, on the 40th anniversary of Ultima 4’s launch), Shattered made the decision to open-source the project and step away again.

On this day 40 years ago, Ultima IV: Quest of the Avatar was released for the Apple II. Its non-traditional goal of improving yourself instead of fighting the flavor of the day antagonist set a new standard for games and gaming. Today, Ultima IV is still often included in lists of top video games of all time and games you must play before you die.

I’m not even sure that Ultima IV is my favorite game, but for whatever reason, I’ve kept coming back to it over and over again as my sandbox project to answer the question “What would legacy games have been like if the Internet existed back then?” I’ve worked on this project on and off for decades, releasing the first incarnation around 2004 under the name “Ultima IV Multiplayer.” Another incarnation added a scripting language and moved all of the game logic into scripts, and another added support for Ultima I, Ultima II, and Ultima III. The latest incarnation, released today, adds support for 12 tile graphics sets, fixes hundreds of bugs, and makes general improvements.

I wanted so much to de-make later Ultima releases like V-VIII, finish adding all of the tile sets from various platforms, upgrade the legacy OpenGL renderer, and offer support for other platforms and languages. I could probably work on this project for another decade if I wanted, but I think it’s time for me to spend a little more time outside of Britannia. Therefore, as a gift to the community, I’ve decided to make the project open source in the hopes that someone else will pick up the ball and run with it. Under their guidance, hopefully Britannia will flourish…

You can find download links for both the 40th anniversary build of CUO and its source code at Shattered Moon’s GitHub page, or at the project entry here at the Codex.