It's just not terribly original.
Girl (usually boy, admittedly) with amnesia is brought out of her everyday life by specific event, goes on adventure, finds out about her past, encounters love at first sight (very bad in a videogame because of the difficulty in building character and tension) who proves crucial to adventure, but is kidnapped (often killed, in stories), goes on to kill a god(-like being)...
Grossly oversimplified, but the cliché parts stand out. A lot. Amnesia in particular is something I no longer accept as possibly being part of a good story.