I generally recommend avoiding computer games generally, as that was possibly the activity that was most destructive to my life, being that it was the only thing I basically did from age 14(?) to 26. Granted, I did do other things, such as high school activities, but getting into the habit of doing it all the time, and then going to college, where there were no external restraints, was a real problem.
TV is mostly a waste of time, too.
I wouldn't recommend avoiding computer games
entirely, though. As a tool for training mental agility and flexibility, I don't think they can be beat. "Here's an entirely alien environment that operates on a whole different set of rules from anything you've encountered before... go!"
