Until today, the only Legends product that is still being released is the video game Star Wars: The Old Republic, along short stories published at the Star Wars blog.
The Expanded Universe had a continuity with few wrinkles.
Some of these creatures have made it into film, while others, because of the way stories unravel, have not (so far). For once something is created, no matter what the context, it takes on a life of its own." A turning point was reached when West End Games began publishing the Star Wars roleplaying game in 1987.
In order for players of the roleplaying game to create new adventures, West End Games needed to provide supplemental material describing the Star Wars universe in previously unknown detail and to make it self-consistent and coherent.
But these were not stories that I was destined to tell.
[…] Since our movies have their own internal continuity, we maintain that in the spin-off works.
Technically, George Lucas has been doing continuity all along by mapping out the nine films.
As an example, the Aurebesh alphabet was originally a random piece of set dressing used in Return of the Jedi.
Stephen Crane copied those symbols and turned them into a complete and workable alphabet which would later be used in the prequel trilogy.