And Now For Something Completely Different

...Ok, maybe this won't be very different after all...But I'm going to invoke the British for the first time, so why not drag Monty Python into it somehow?
Check out this research from the British Board of Film Classification into some of the causes and effects of playing video games. The immediate focus seems to be on whether or not video games cause violent behavior, but they actually get to some *interesting* things as well:

gamers appear to forget they are playing games less readily than film goers forget they are watching a film because they have to participate in the game for it to proceed. They appear to non-games players to be engrossed in what they are doing, but, they are concentrating on making progress, and are unlikely to be emotionally involved

My own take on this is that because there are goals and rewards in games, the analytical part of your brain is active - trying to optimize behavior and accomplish tasks. In non-interactive media, you are free to simply experience...Which means 100% of your brain activity can be the artsy, passionate side, meaning you'll have more of an emotional investment in the story & characters. If you are playing a game, you may have some investment in the story & characters, but most of your emotional response will tie directly to your performance as it relates to the goals and rewards in the game...

gamers claim that playing games is mentally stimulating

Despite the fact that it looks like Junior is a vegetable plugged into his Nintendo, due to the presence of goals and rewards in games and the need to optimize behavior (because there is always a cost to sub-optimal play, even if it is simply the wasting of some time), his mind is actively assessing and prioritizing actions while his body performs the same.

non-games playing parents are concerned about the amount of time their children, particularly boys, spend playing games and would prefer that they were outside in the fresh air

While I've spent an awful lot of my own life playing games, I do think it's important to have balance in all things. My little girl is giving me plenty of outdoor exercise these days to complement the time I spend working on games.

female games players tend to prefer ‘strategic life simulation’ games like The Sims and puzzle games and spend less time playing than their male counterparts;
male players favour first ‘person shooter’ and sports games and are much more likely to become deeply absorbed in the play.

Hooooboy, time to open up Pandora's XBox!! (Even though this conclusion shouldn't surprise anybody who has thought about games beyond "I like Monopoly.")
Women are physiologically wired to nurture and raise families, which is an ongoing process, a life-long experience. Men are wired to kill animals and bring them home for supper, which is a goal-oriented, win/lose scenario. Games are models for real-life, so is it any wonder that players are drawn to the games which model their own life? And men play longer because part of their model is winning, and the best way to win is to practice, and that takes more time than simply "experiencing".

Note that as human beings, we are self-aware. This means that any one of us can identify and change our thinking and behavior; doing so then changes the set of games that model your life. So a woman who likes playing Halo has adapted her thinking and worldview such that it is no longer the same if she had been sitting around a cookfire 10000 years ago; a guy that likes the Sims may not have an outlook on life that is quite the same as if he were responsible for bringing meat to that same campfire 10000 years ago...

Going back to the first point, the big win from the BBFC report (which, surprisingly, comes right from the Director of the Board!!!) is:
We were particularly interested to see that this research suggests that, far from having a potentially negative impact on the reaction of the player, the very fact that they have to interact with the game seems to keep them more firmly rooted in reality. People who do not play games raise concerns about their engrossing nature, assuming that players are also emotionally engrossed. This research suggests the opposite; a range of factors seems to make them less emotionally involving than film or television

The only point I want to quibble with here is that gamers can have tremendous emotional investment in their game - but it is tied to their personal investment and performance (and not the fates of characters as it would be in a movie...)