My humble opinion is that you've got a good outline for a story (and a far better knowledge of grammar than the majority of people who post here on AB) but you need to tell the reader more about what the characters are thinking and feeling.
Also, try to avoid an opening line which effectively says "this is where we are and this is what's happening". (It's a great style for journalism but lousy for fiction). Try to involve the reader by jumping straight into the story. For example:
"Cute, cute, cute". Crystal found herself speaking the words out loud. She looked around, afraid that someone might have come into her bedroom unnoticed while she was playing the computer game. Realising that her concerns were without foundation, she smiled. After all,why should she feel embarrassed simply because she recognized a special quality in one of the game's main characters? Demyx was special to her. She couldn't quite put her finger on the reason why (and she'd long since given up trying to explain it to her friends), but she felt that she meant as much to Demyx as he did to her. Logic, of course, told her otherwise, but logic and love seldom go hand in hand, especially when you're fourteen years old.
That paragraph isn't meant to be perfect. (I've rattled it off in the same time as it takes to type it. It's also gone 3.00a.m and I shouldn't have opened that last can of lager). However, I've tried to illustrate that you can tell the reader that Crystal is in her bedroom, that she's playing a computer game and that she's 14 years old, almost incidentally, thus avoiding your rather dull opening sentence.
Chris