As a gamer it hurts me to say it, but video games do not translate into movies well. Video game movies tend to be poorly reviewed and underwhelming in terms of their box office returns. Even if a video game movie (like Need For Speed) does manage to be profitable, the reviews tend to be less than favorable. Consider that since 1993 around 30 video game movies have been made and released internationally. Of those films (which include titles such as Super Mario Bros., Street Fighter, Mortal Kombat, Hitman, Lara Croft: Tomb Raider, Final Fantasy, and Resident Evil) none had a rating higher than 50% on Rotten Tomatoes (the highest being Final Fantasy: The Spirits Within at 44%). At least 10 of these were below 10%. Only Prince of Persia: The Sands of Time and Mortal Kombat scored higher than 50/100 on Metacritic. It isn't that they couldn't make good movies, but few seem to be able to create a film that satisfies both gamers and critics. Worse yet while a video game movie will appeal to a set audience, unless it can garner a positive critical response, it's unlikely the general film going public will take a chance on it.
For the most part games can succeed whether their stories are particularly good or not. Graphics, gameplay and replayability factor into a game's success where a film has to succeed in terms of its characters and story alone. Video games and movies don't usually share the same story structure, and the sorts of things that make a game fun don't factor into a feature film.
The story mode in games tend to last anywhere from 6 to 20 hours depending on the type of game. Then there's the additional content like side quests, exploration and perhaps even multiplayer modes. A game is a big experience. As important as the story is (or isn't depending on the game), there is a lot more to it than just the story. In fact, few games are played for their story alone. Those that are tend to be the long variety that can't adequately be shortened into a 2 hour film. It's so hard in fact, that some filmmakers try to avoid a straight adaptation all together. Instead they create a new story and set it within the game world and hope the familiar title will attract gamers (again Need For Speed comes to mind).
When you think about it movie goers getting hooked on video game and comic book films seems just as unlikely. Yet comic books are different. Their stories and experiences are more adaptable. And it certainly helps when you have an entire studio devoted to realizing their adaptations on film, not to mention the caliber of talent on board for their projects. Comic book movies have, in recent years, done a good job of modernizing. They look cool, they're fun, and they work in timely issues relevant to the modern movie goer. If serious video games movies want to succeed and become relevant they'll need to adapt similarly.
Then again, there is another type of video game movie coming soon whose rules for success differ from that of a serious game adaptation. Upcoming movies like The Angry Birds Movie, Sly Cooper, and Sonic The Hedgehog will likely be profitable by virtue of their target audience's willingness to see whatever the latest animated film happens to be (especially with names as big as these). Yet that doesn't ensure that they will find critical success.
Video games make lots of money, so it makes sense to want to adapt them into films, and maybe some day they'll be properly and successfully adapted. In the meantime they're a failing genre. It may not sit well with gamers, but it's the truth.