Jedi Knight Jedi Academy
This game expands on Jedi Knight II Jedi Outcast adding new abilities and features. It also has a non-linear level structure and more choices in the story but I think this makes the story weaker than Outcast while still being good. As with Outcast the Multiplayer and bot matches are fun with friends.
There is a mod that is a lot of fun for this one called: Galactic Legacy. It adds hundreds of maps, levels based on the films and other Star Wars media, unites Academy and Outcast into one game, adds a sandbox mode where you can spawn enemies and fight them on different maps, and much more.