In industry the job title of Art Director mainly consists of a person to be the "visionary" in a game who's job is to maintain its visual standards and styles. (It also includes technical understanding). Their main responsibilities tie in with the entire style of the game as well as getting together and leading an Art team. It seems to be more of a managers role so their duties are put towards the entire aesthetic sections of a game. Its very much so a creative role indeed, from the extract that I read from 1 art director inparticulary its quite a stressful career needing a lot of effort, time and work.
It basically seems to be a career where again its deciding the game aesthetics but also about management skills. I would say that there isn't that much of a difference between being an Art director for a game or a film, its the same principal where its about whats seen and designed. With films its viewed in a set perspective dealing with camera angles and shots where-as Games are less restricted, where players can move around freely. It does depends on the game of course, I have seen some where the camera angle is set where the player must be in that specific area. Managing art is equally important in both areas.
It seems to be a very tough job to aim for, it takes a specific person I think to be able to actually consider going for this career. If I was to become one it would need continued sketches, drawings over a long period and experience from working with other companies. Its hard to specify exactly what would need to be done to get to that stage but defiantly drawing/painting and all the other master techniques are very important.