I don't think I've ever been this affected by a second playthough.
When Mage Jenny saved the world, I went back and watched that ending montage on YouTube, over and over, so I could justify my criticism of it. So I could say, no really, I checked. It is NOT ENOUGH. Because it wasn't just a victory montage, it was an Alistair's death montage, and that aspect was brushed aside. I felt liked I'd been denied something important to me.
That same montage, when it was no longer Alistair's death scene, was completely transformed.
And then, when Jenny was back in the throne room, rested and cleaned up again, the final scene was not only no-less-affecting because it was my second time, it was actually more important to me because of my first game.
I mentioned before that I once experimented with having Jenny give Alistair a bunch of coal and smelly onions to see what he'd say when his approval dropped. And after restarting the game so that "never happened," Jenny made out with him a few times just to reassure me that I hadn't actually ruined anything. See, look! He's still in love. It's okay.
I find myself wanting to watch the coronation scene again, and probably again after that, to reassure myself that I can.
Not only can't I think of another game that has done this, I'm not sure how another game could. Perhaps if I had learned, after playing Apostate Jenny of Sad Consequences through to the end, that if she had been more critical of Anders, he might not have chosen to blow up the Chantry, and that some other terrible event would cause Meridith to call for the Rite of Annulment. It would not only have been devastating to see the consequences of Jenny's well-meaning actions, but it would have been a relief to fight that last battle with Anders, knowing that he hadn't caused it. But even that isn't quite the same. I can't think of another way that the game could end the same way but not mean the same thing.
I know, I know, I just declared DA2 the Best Game I've Played. I find myself thinking, no, maybe Origins is! But I don't know how to compare the two. They succeed so differently, for such different reasons, and on such different levels. I can go through all the things that could be improved, but what they get right, they get RIGHT. And it's amazing to experience.