I know someone whose first Final Fantasy game was Crisis Core. He didn't even realize that there was another FF7. He thought that was it. So he had no idea that Zack was doomed.
It's funny, though, because he played to the end of the game and was utterly confused to no end by Zack's death. He approached me one day, said something along the lines of "you play Final Fantasy, right? You know FF7? What was up with the ending? I mean, after everything that happened in the game, he just... died in the end? WTH!?"
It confused me at first, but after some more conversation, I figured out what he was talking about, and I was like "uh... dude..."