Jedi Knight made use of a significantly more powerful game engine than its predecessor, providing fully 3D environments and objects. It was one of the first games to ship with support for hardware 3D acceleration, through Direct3D 5.0, although it can also be played in a software-rendered mode. The game includes support for 3D sound effects through DirectSound and A3D 1.0 and uses CD audio for music.
Kyle retrieves the Valley's location from 8t88's decapitated head after a pair of Dark Jedi kill the droid. Kyle and Rebel agent Jan Ors travel to Ruusan, on which the Valley is located, and Jerec captures Jan. Kyle's decision to either rescue Jan or let her die dictate whether Kyle becomes aligned with the dark or light side of the Force. With both paths, Kyle has a final confrontation with Jerec in the Valley of the Jedi's core. If the player chose the dark path, the game ends with Kyle becoming emperor; if the player chose the light, the game concludes with Kyle carving a monument to his dead father.
Jedi Knight requires the player to make ethical decisions as part of the gameplay. Kyle is a neutral character for most of the game, neither fully light nor dark. Actions against unarmed civilians, as well as the Force powers a player chooses, sway Kyle toward the light or dark side. Eventually, the character definitely chooses a side.
Enemies include a range of Imperial characters as well as various alien creatures and robotic entities. In addition, the player occasionally faces more powerful foes such as the AT-STs. The game's "bosses" are a series of Dark Jedi. In addition to hostile individuals, there are also non-combatant civilian characters.
The lack of dedicated servers created difficulties in lag time for online play. Messages sent were never centrally processed, and so a "hit" in one person's frame rarely guaranteed an actual event. Players compensated for lag by shooting ahead of the opponent so as to register a hit on the opponent's computer. At times, the game suffered from extensive cheating, until the third-party program "Kicker Helper" was released. JK's permissive checksum system allowed most of the "hacks" or "cogs" (as the cheats were commonly called) to work. The physics engine and Force system, however, are so permissive that many legitimate actions were construed as cheating. In addition, the open nature of the game's programming allowed users to create customized skins for characters, and custom maps with relative ease; some cogs were created not as cheats, but as modifications to create new gaming dynamics.
During the period of the game's heightened online popularity (1998-2002), the Massassi Temple (www.massassi.net) served as a central hub of the modding community, housing thousands of user-created levels, multiplayer characters (skins), and gameplay modifications.
Jedi Knight was a nominee in the 2000 Satelite Awards in the Best Interactive Product / CD ROM Game category. In March, 2004, GMR Magazine rated Jedi Knight the fourth best Star Wars game of all time.
Released four months after Star Wars Jedi Knight: Dark Forces II, the Star Wars Jedi Knight: Mysteries of the Sith expansion pack expansion features the opportunity to play as Mara Jade, an apprentice to Kyle Katarn. Kyle eventually leaves to investigate a Sith temple and the player assumes control of Mara. After completing several missions for the New Republic, Mara searches for Kyle. Mara discovers that he has succumbed to the dark side, but she manages to bring him back to the light.
This expansion adds colored lighting effects, new enemies, weapons, and Force powers; it also removed the light and dark side distinctions. Multiplayer received two new game modes: Kill the Fool with the Ysalamiri (a variant on "tag") and Lightsaber Training (a mode for ranked Jedi in saber combat in specific arenas). Multiplayer also expanded to include "personalities", a class system that could be applied to other game modes except for Lightsaber training. Capture the Flag was removed.
There were several under-the-hood changes as well, the most significant involving COG, the programming language that Jedi Knight uses to create scripted in-game events and interactivity (doors, elevators, weapons, in-game cutscenes, etc.). Rather than full-motion video cutscenes, the game uses recordings of game-engine-generated events overlapped with voice acting. The option to use high-resolution sounds was eliminated. Some basic anti-cheat protection for multiplayer was included as well. The expansion was typically sold separately from Jedi Knight, but required the original game to install.