Ultima Online (UO) is a fantasy massively multiplayer online role-playing game (MMORPG) released on September 24, 1997 by Origin Systems.
Set in the Ultima universe, it is known for its extensive player versus player combat system. Since its release, it has added eight expansion packs, a booster pack, and dozens of free content updates. The release of Kingdom Reborn in 2007 brought a new game engine with upgraded visuals.
In preparation for the launch of the Stygian Abyss expansion, support for the existing client was discontinued to optimize the patching procedure. As a replacement, a revised rendition of the Kingdom Reborn client emerged, rebranded as the "Enhanced Client." This revamped version was unveiled as an open beta in July 2009, coinciding with the release of Stygian Abyss.