I agree completely about Mortal Kombat. Its one if the few that I feel were done right.

Though I think non gamers can enjoy video game movies, just as people who have not read the book a movie was based on can enjoy that.

A compelling story should be able to work when translated to another medium. I doubt Harry Potter would have worked if they changed Hogwarts into a government agency, made Harry a grizzled 45 year old wizard cop and turned Voldemort into a space vampire.