Star Wars Jedi Knight: Mysteries of the Sith is an expansion pack for the first-person shooter Star Wars Jedi Knight: Dark Forces II. It was developed and published by LucasArts, and released on January 31, 1998. The expansion includes a single-player mode and fifteen multiplayer maps. The multiplayer mode allows up to eight players to play online or over a Local area network. It was re-released onto Steam along with its predecessors and sequels.
The single-player story is set five years after the events of Dark Forces II. The player controls Kyle Katarn, protagonist of Star Wars: Dark Forces and Dark Forces II, and later in the game, Mara Jade, one of the most popular Star Wars Expanded Universe characters.
There are also technical improvements over Dark Forces II, including colored lighting, new textures and models, and improved artificial intelligence. Mysteries of the Sith received mostly positive reviews from critics, with praise being given to the game's story and improvements to artificial intelligence.
Mysteries of the Sith is primarily a first-person shooter, but offers the choice of a third person view. Unlike Dark Forces II, where the player's actions within the game dictate whether the story ends with the light side or the dark side ending, Mysteries of the Sith has a single, morally positive course. The player progresses through the game in a linear fashion; there are fourteen levels and each has set objectives that the player must complete before being able to continue to the next level. Within each level the player can encounter both hostile and non-hostile non-player characters (NPCs). As well as including some enemies that featured in Dark Forces II, Mysteries of the Sith adds twenty new monsters, including a rancor. Some non-hostile NPCs may help the player by attacking enemies.