UltimaXNA is a isometric massively multiplayer online role playing game client. It is programmed in C# and uses the XNA framework for graphics and audio. In its default configuration, it can use the data from any Ultima Online installation released prior to Stygian Abyss. In tandem with the RunUO server, it provides a framework for video game development.

At this time the project is functional but not feature complete.

Development started May 2009 and continued through through February 2010. UltimaXNA is not under sustained development at this time.