Star Wars: Jedi Knight -- Dark Forces II (with Mysteries of the Sith) combines Star Wars: Jedi Knight -- Dark Forces II and its add-on pack, Star Wars: Jedi Knight -- Mysteries of the Sith, together in one package. Neither the game nor the add-on pack have been altered in any way; they're simply sold together as one product for this version, with the same number of discs (3) and instruction manuals for both titles.
In Star Wars: Jedi Knight -- Dark Forces II (with Mysteries of the Sith) you have the option of controlling the Jedis Kyle Katarn or Mara Jade, depending on which title you load up. Playing the game in order would mean completing the Star Wars: Jedi Knight -- Dark Forces II portion before moving on to the companion missions (as they take place five years after the events of the main title). As Kyle Katarn your goal is to make your way through twenty-one mission-based levels in pursuit of Jerec, a Dark Jedi who was responsible for your father's death, and who is himself pursuing the unimaginable power buried in the Valley of the Jedi. Significant only to the main title, as Kyle Katarn you will have to make decisions along the way that determine whether you want to serve the forces of good (defeat Jerec and protect the Valley of the Jedi from being disturbed) or evil (defeat Jerec and steal the power buried in the Valley of the Jedi for yourself).
In the add-on pack you start out as Kyle Katarn and then, when he is called away to investigate a Sith temple, you take over the role of Mara Jade, a Jedi who has been training under Kyle Katarn since being persuaded by Luke Skywalker to abandon the dark side of the force. The Mara Jade missions (the last ten of the fourteen missions included with the add-on pack) involve protecting a Holocron and carrying out negotiations with a Hutt crime boss, but soon enough Mara Jade finds herself a caught in the ancient world of the Sith, where she must ultimately face a confrontation between good and evil.
The only significant difference between the two titles is that in Star Wars: Jedi Knight -- Dark Forces II you have the ability to choose your moral destiny, allowing Kyle Katarn to complement his neutral force abilities (Speed, Jump, Pull and Seeing) with either good or evil secondary powers (such as Healing and Persuasion or Throw and Grip), while the add-on pack starts you out with the assumption that Kyle Katarn and Mara Jade have chosen the light side of the force. Some of the weapons that Kyle Katarn gets to choose from throughout the game are rail charges, bryar pistols, thermal detonators and concussion rifles, while Mara Jade's primary weapon is a purple lightsaber, which she earned during her Jedi training.
Both games can be played in either a first- or third-person point-of-view, both include the standard FPS fare, such as armor-ups and health packs, and both rely on cut-scenes to fill in the story, although the Star Wars: Jedi Knight -- Dark Forces II cut-scenes are done in full-motion video, while the mission pack's are of the animated variety. For Internet play, both games allow you to test your Jedi skills by taking on up to seven opponents online, all the while rising in rank based on your achievements.
Set in a universe familiar to a wide range of fans, Star Wars: Jedi Knight -- Dark Forces II (with Mysteries of the Sith) provides two popular titles together in one package. Whether you deem yourself a champion of the light side or an apprentice of the dark, you'll have a total of thirty-five missions to test your convictions, as well as your mettle. May the . . . well, you know the rest. ~ Gil Shif, All Game Guide