Five years after the events from the award winning Knights of the Old Republic, the Sith Lords have hunted the Jedi to the edge of extinction and are on the verge of crushing the Old Republic. With the Jedi Order in ruin, the Republic’s only hope is a Jedi Knight struggling to reconnect with the Force and is faced with the galaxies most dire decision: To follow the light or succumb to the dark side…

• The Sith Lords is the next chapter to Knights of the Old Republic; winner of more than 35 “Game of The Year Awards” featuring an all-new and perilous storyline set approximately 4,000 years before Star Wars Episode I.
• All-new Force powers, weapons, locations, characters and classes add to the richness of this next epic installment.
• Choose from three different classes of Jedi to start the game with access to specific Jedi abilities.
• Choose the light or the dark side of the Force based on your characters actions as you progress through the story. The choices you make not only affect your character, but also those in your party, and those who may join you in your quest.
• Cameo appearances from memorable characters of the first game enhance the continuity and story flow through this unique time period.
• Additional content will be available for The Sith Lords via Xbox Live.
• Developed by Obsidian Entertainment, the development house founded by members of the Fallout, Icewind Dale, Baldur's Gate, Dark Alliance, and Planescape: Torment teams

Official fact sheet from LucasArts.