The first runthrough, plot beats everything. Backstory is what keeps it relevant and alive. A story with no backstory is just a story - you go through it, hopefully enjoy it, and are done with it. Backstory to explore and learn about and speculate on keeps you invested and deepens the characters. One of my favorite animes is Blood+ because of how realistic and believable the characters are. They act according to their experience and personalities in such a way that real humans would and are dynamic in the literary sense over the course of the story. You slowly learn more about the characters and their backstories and lives and begin to understand why each one acts how they do. The most convoluted is Hagi, who you wonder about the entire time until all is revealed and everything makes sense. It sounds cliché, but it's well done and other media should take note. Backstory is powerful and deepens the experience, causing it to remain in the audience's minds longer.That said, I probably enjoyed HL2 Ep2 more than anything in a long time, and that universe's "backstory" is known well enough to the point that there was little to wonder about in the game. The story and presentation were bonanaza amazing enough that I remember it just as well.