You have to decide what kind of story you're going to tell. For instance I would argue a movie like 'Toy Story 3,' which isn't realistic at all, is really emotional and involving. It just depends. I played this game called 'Superbrothers: Sword & Sworcery EP' for iPad that is totally old school 8-bit, which I found very moving.
Sentiment: POSITIVE
While films are a very visual and emotional artistic medium, video games take it one step further into the realm of a unique personal experience.
So if you want to have a great video game-based movie you have to keep the mood of the game, use the normal character setup - but you have to flesh out the story and provide more background for the characters.