Everything has changed
It is a dark time for the Star Wars franchise - well, depending on your point of view. When Disney took the reigns of the Star Wars license, the company took the massive, convoluted Star Wars universe and trimmed the fat. Everything except for the Star Wars: Clone Wars TV show and movie, Star Wars: Rebels, prequel movies, the original trilogy is no longer considered canon. The entire Expanded Universe has been hacked off, leaving only a severed stump of what came before, but, on the bright side, the future growth of the franchise is free to develop into something new.
So, much of what we knew of the Star Wars universe is no longer true. But with new Star Wars games, movies and books coming in the future, there could still be much to learn of the Force, the series' space-faring characters, and the worlds that have filled the fiction for so long. But, more importantly, events that were once set in stone are going to change. The Star Wars games in particular have established some essential plot points in the grand scheme of the galaxy far, far away. Now, we're going to have to wait and see how these events get their official explanation in the new canon.
We don't know how the Rebellion gets the first Death Star Plans
It looks like the new canon will have this event covered pretty soon. Rumors are circling that the Rogue One: A Star Wars Story movie will tell how a rebel strike team pulls off the Death Star plans heist. But before it was cut from canon, the Death Star's weakness was exposed by none other than the former Imperial Stormtrooper Kyle Katarn in Star Wars: Dark Forces.
In the Dark Forces version of the event, the Rebel Alliance hires Katarn to infiltrate an Imperial base that houses the plans. Being one of the earliest missions in the game, stealing the Death Star plans kicks off Kyles career as a rebel agent. Though it was interesting to have one of the Extended Universes well known characters spark the chain of events that let to the destruction of the first Death Star, Im more interested in seeing how the the new canon fleshes out this seemingly minor event in the lore.
Where does the Rebellion's sweet starbird symbol come from?
Star Wars: The Force Unleashed may not have been the most praised Star Wars game, but the story fleshed out some significant details in the Star Wars universe. We all know of the struggle of the Rebellion against the Empire, but who got the rebellion started, and where did they get the idea for that amazing starbird symbol? In The Force Unleashed, it all began with Darth Vaders secret apprentice.
Galen Marek (Starkiller) was a Dark Jedi that turned to the light after being betrayed by his master, Darth Vader. His story details how events unfolded toward the end of Vaders galactic purge of the Jedi. After being betrayed, Marek meets an old jedi master, makes friends with the Organas (Princess Leias adopted family), turns to the light, and takes on Vader and the Emperor himself in the newly constructed first Death Star. After he falls, saving the future leaders of the Rebellion, his actions and defiance of the Empire inspire them to form the Alliance and adopt the Marek family crest as the symbol of their organization. In the new canon, the start of the Alliance is currently being told in the Star Wars Rebels TV show.
Wedge Antilles is a nobody
Without the Star Wars games and Expanded Universe to flesh out his character, Wedge Antilles is just "that one lucky pilot that survived both Death Star battles." In the Star Wars: Rogue Squadron series, players do get to sit in the cockpit as heroes like Luke Skywalker, but much of the time you're running missions as Wedge after Luke hands off the Rogue Leader responsibilities to the skilled pilot.
In the Rogue Squadron games, Wedge and Rogue Squadron are a huge pain in the Empire's ass as they run missions to destroy weapons facilities, steal the Imperial shuttle that is used by the Endor strike team, and even defend the Mon Calamari homeworld years after the second Death Star went BOOM. Wedge just might be the greatest hero the Alliance has ever seen, but now he's just the guy that flies behind the Millenium Falcon.
What has Luke been doing after the Empire was defeated?
Before the EU cut, we had a pretty good idea what Luke was up to after his confrontation with Darth Vader and the Emperor at the Battle of Endor. Star Wars: Jedi Outcast (and plenty of novels and comics) shows that the hero becomes a full Jedi Master, establishes a new Jedi order, and even trains Kyle Katarn in the ways of the Force in the post-Empire galaxy. Now, Luke is a huge mystery.
We will be getting a better idea of what Luke has been up to after the Battle of Endor in the new movies, but judging from the state of the galaxy in The Force Awakens and the fact that the Jedi have seemingly faded into legend, Luke hasn't brought back the lightsaber-wielding protectors of the galaxy like he did in the Expanded Universe.
Dash Rendar doesn't exist
The N64's Star Wars: Shadows of the Empire filled in the gaps between Episode 5 and 6, detailing the adventures of the mercenary Dash Rendar. The hero is a critical character in the events leading up to Return of the Jedi, starting his journey at the Battle of Hoth and eventually playing a key role in taking down Prince Xizor, the leader of a powerful criminal organization.
Along the way, Rendar attempts to intercept Boba Fett as the bounty hunter transports the carbonite-frozen Han Solo to Jabba the Hutt. The mercenary prevents Luke from being murdered by Jabba's thugs. He even prevents Leia from becoming a slave to another vile gangster. If it wasn't for Dash Rendar, the Rebellion's heroes would never have seen the fall of the Empire.
What was the galaxy like 1000 generations before the Empire?
As far as the new canon is concerned, the Old Republic timeline as seen in games like Knights of the Old Republic and the MMO Star Wars: The Old Republic doesn't exist. So, we don't know anything about the official universe before the Clone Wars. And no, anything new that comes out of SWTOR doesn't count.
In games like KOTOR, and SWTOR, we've had a chance to run through the bustling, crime-filled streets of Nar Shaddaa, see the vistas of Alderaan thousands of years before the planet exploded, and explore the ancient Sith temples of Korriban. Now, any new Star Wars story set in the Old Republic time period can change our perception of the ancient galaxy, because it doesn't need to follow the old visual and technological templates. The new Old Republic could look like anything: Jedi could wield swords, ships could look more primitive, and blasters could get even less civilized and shoot solid projectiles. There are unlimited possibilities. The Old Republic is a blank canvas again, ready for game developers, filmmakers, and novelists to fill in the thousands of years gap.