The Lost Jedi

The Lost Jedi is a duology of Star Wars Expanded Universe Choose Your Own Adventure novels released in the UK in the early '90s. The player character, the Lost Jedi of the title, is Havet Storm, a Jedi, the hitherto unnamed Rebel who sent the Death Star plans to Princess Leia's ship, and the nemesis of Boba Fett. The series is notable as being the first Star Wars Expanded Universe series to kill off a movie character (Han Solo), albeit in a non-canonical bad ending.

The Lost Jedi consists of:

Arch Enemy: Boba Fett in both books.
Ascended Extra: Havet Storm.
Bittersweet Ending: The end of Jedi Dawn. You've got the Death Star plans to Princess Leia and A New Hope can progress as scheduled. Too bad your girlfriend the Mad Scientists Beautiful Daughter turned out to be loyal to The Empire all along, killed your ally and best friend and tried to kill you.
Choose Your Own Adventure: of course.
Downer Ending: As mentioned, one non-canonical ending sees Han dead and the Rebellion on its last legs.
Dropped a Bridge On Him: Havet Storm got unceremoniously killed off in a single sentence in a Wizards of the Coast web fiction.
The Empire and La Résistance: It's an original trilogy era Star Wars Expanded Universe series.
Mad Scientist: One of the antagonists in the first book, the designer of the Death Star's superlaser.
Mad Scientists Beautiful Daughter: Subverted when she realises that you used her to get to the superlaser plans and tries to kill you.
No Export for You: The Lost Jedi, like many Choose Your Own Adventure adaptations of popular media franchises, didn't see release outside the UK.
Paper Thin Disguise: Diamond disguises herself as Facet by wearing a wig. Vermillion/Scarlett/Crimson passes himself off as three seperate people by wearing a different item of red clothing for each persona. Hilariously, Havet can have close interactions with all five depending on the player's choices and not see the similarities.