Edge of Darkness

Edge of Darkness replaces The Sith Lords with an entirely new campaign. You play Nemesis, a dark Jedi serving the True Sith Empire, in a story set a century before The Old Republic, with new planets, characters and music. The installer is a large Windows executable that applies the conversion to your Knights of the Old Republic II installation, so it should be run on a copy you are happy to modify: it cannot be uninstalled and saves from before will not work. The authors ask you to turn Frame Buffer Effects off in the game's graphics options. Expect about five and a half hours of play.