While the Expanded Universe of Star Wars has been wiped out of existence, there remains certain legacy items that have aged remarkably well. In addition to being terrific storytelling, the take place millennia before the films. Therefore, the events of The Force Awakens have not necessarily contradicted the events therein.
Knights of the Old Republic
PC Roleplaying, 2003
This is a quintessential Star Wars story. You can choose to be a valiant hero, or a dastardly villain, and either save the Republic from the Sith, or to subvert the Jedi and seize control of the Sith armada. The story heavily draws upon classical mythological archetypes. While not entirely original, it is deeply satisfying.
Knights of the Old Republic II: The Sith Lords
PC Roleplaying, 2004 While the game engine is the same, the tone of this entry could not be any more different. Moral ambiguity abounds—this is no mere tale of light and dark. Instead, it features some of the most mature writing of the Star Wars franchise. Though be advised: you have to play this with the Restored Content Mod, available on Steam, for a satisfying experience.
The Knights of the Old Republic
This comic is technically a prequel to the first video game, though it does not require you to have played the games in order to enjoy it. It follows Zayne Carrick, a Padawan betrayed by his masters and framed for the murder of his fellow Jedi students, all for reasons unknown. Fleeing the Republic, he falls in with with a gang of disreputable scoundrels, struggling to both survive—and clear his name. This title combines both serious stakes for the franchise, as well as the sense of whimsy that made the Original Trilogy so entertaining to begin with.
The Darth Bane Trilogy
This trilogy of novels takes place several millennia after the Knights of the Old Republic series, but hundreds of years before the films. It follows Dessel, an enslaved miner, as he escapes the shackles of his servitude, to rise to become one of the preeminent Sith of his era… and more. As Darth Bane, he will establish many of the practices that will ultimately define the Dark Side as practiced by Vader and Palpatine.
Jedi Knight II: Jedi Outcast
PC FPS, 2002
While this takes place in the era of the Expanded Universe, it still stands as a foundational entry in the franchise. Kyle Katarn is essentially a Han Solo type of rogue and scoundrel that has discovered he is descended from a long line of Jedi, and must reclaim that heritage in order to stop a new threat. Critically, the game engine still holds up as eminently playable, even 13 years later.
1996-2012 Start with Rogue Squadron by Michael Stockpile, and get ready for a wild ride. If you liked Poe Dameron, you’ll get a kick out of Corran Horn, a former spy turned X-Wing pilot, who has to fight to restore order in the Galaxy a mere two years after the Battle of Endor. It may no longer be canon, but it remains quality dogfighting action.