Cute story told backwards with an unexpected happy ending
The main story is actually told backwards, ala the movie Memento. While not the most original concept, still a cool way to tell a story. In the end there is quite the happy ending that will result in many tears being shed.
As the story progresses the characters attitudes and emotions change in response to the ever evolving story. This makes for what is a very well written game that makes the story and characters seem genuinely real.