No two people in Oblivion look alike, and every speaking character in the game has lip-synched dialogue performed by real vocal actors. And we mean actors: Bethesda, the game's developer and publisher, hooked up with top Treker Patrick Stewart to voice the king. However, the story feels like classic been-there-done-that fare: sinister tragedy leaves a kingdom leaderless, terrible curse revealed, the aforementioned gate to Hell opens, oh-my-God-the-pain, epic quest ensues.
If you aren't down for the sort of scripted experience that the main story provides, that's cool too; you can instead make your own adventure by exploring the incredibly realistic world. There are scores of quests and hundreds of hours of gameplay whether you follow the main storyline or not. That's the beauty of it; just as you have a choice how you spend your time in the real world, you have a bunch of choices as to how you spend your time in this in-game world.