Dutch wrote:
A lot of books utilize similar sorts of plot devices, particularly fantasy books like Lord of the Rings and Wheel of Time. Though you don't directly find the Eldridge until much later, it indirectly effects the plotline throughout. Miang, who largely resembles the opening character, appears much earlier; for example. I didn't think of Xenogears right away, but it had a very effective beginning in my opinion.
To add another, Chrono Crosses opening was better than everything else in the rest of the game; at least the first time, after a while it started to annoy me somehow.
Eldridge did not indirectly influence anything other than that it created the world. As the player you're oblivious to its, and Deus's, existence for about 80% of the game with absolutely no way to find out. It's like saying 'Let there be Light' in the Bible influenced everything else that happened in the Bible because otherwise there wouldn't be a world.
The person in the opening was when Miang/Elly was one person (Miang = bad, Elly = good). It would take a considerable leap of logic to deduce that she was Miang since the only thing they had in common was purple hair, and she wasn't Miang anyway. Miang had little influence in the grand scheme of things and her existence is mostly just another reason to read Xenogears Perfect Works.
Chrono Cross probably wins the award for coolness, but the intro is devoid of meaning. I assume the part that is supposed to have any meaning is the beach part, which actually doesn't have any meaning when you actually play the game. I liked the opening of CC, but it'd be nice if there was actually some kind of coherent theme or deeper meaning beyond a cool soundtrack and a bunch of CGs.