Homeworld showed me just which kind of story I like. The initial hopefulness with the Mothership being built, then a crushing depressing bit, Kharak being destroyed, the bulk of the story being made up of a rather desperate struggle, ending rather bittersweetly. If you think about it, a lot of media goes like that. Battlestar Galactica, KotOR, Deus Ex: HR, Fallout 3, Mass Effect, all follow the basic structure of hopeful intially, major defeat, the hard journey and the bittersweet ending.