When it began, the Mass Effect series really broke down the door in a lot of concepts. Many of these concepts might not be the first time they were attempted but it was the first time it was done well. What was your favorite "aspect" about Mass Effect?
For me there is really only two:
1. The ability to import your player and players.
I can't think of an rpg, off the top of my head, that has done this besides Mass Effect. And if it had been done before, it was certainly done better in the ME series. For me, being able to import your character was like taking part in not only a trilogy or saga but your own continuing story and events. I think a lot of RPGs just miss out on this concept. Where in a Bethesda rpg, its only a continuation of the hodgepodge lore but never a single identity. Some developers will just slap on sequel title and completely change all the lore and characters with no relation like Squaresoft with Chrono Cross. This was a huge game-maker for me, and I just snub at other rpgs when I think about this concept.
2. The ability to have multiple relationships included into the story.
I believe other rpgs have scratched on this area, but Mass Effect really crowned it. Being able to have a relationship and friendships with multiple characters and alter the storyline depending on how you treat those friends.
What other concepts in Mass Effect do you wish other RPG developers would emulate?