The point is that all our discussions about the plot in the game are based on the idea that the universe we're talking about actually exists. Not just that, but we are imagining ourselves as being inside it. Of course it is actually a game, but there's no sense in mentioning that when explaining stuff.

I mean, Squall won't do anything unless we make him do it, but that doesn't mean we're going to try to explain his actions by appealing to the gamer!