I honestly think that if this was a novel it would have a real chance of becoming required reading for 7th-10th graders. Early on in the game I was a bit put off by the fact that the gameplay is somewhat lacking compared to many modern titles, but after about an hour I couldn't have stopped if I wanted to. The story (which oddly for a 1st person game is not about the character you're playing, but that character's younger sibling) is utterly fantastic, it's downright beautiful. Before this I never would have considered giving a game that took me ~2 hours to complete (with lets be honest, less than stellar gameplay) a perfect score, but I'm not kidding when I say that the story (for me at least) made up for everything else. I was totally engrossed to the point that I was literally crying at the end.
I have a feeling this is a game that will stick with me in a way that very few games ever have, and wholeheartedly recommend it to anyone looking for a great story.