siliconwafer writes: "An article in The Economist raises some interesting points about addiction to video games, drawing from psychology and sociology to describe why certain people prefer certain types of games, and why they might become addicted to them. It is suggested that to discourage addiction, game designers could have their games recognize addictive behavior and respond to it by encouraging gamers to take breaks. Do game designers have any responsibility to recognize addictive behavior, or does this responsibility fall solely on the gamer (or the gamer's parents in the case of a minor)?"
(Testing to see if comments are still working, but while I'm at it, and to keep things on-topic...)
Keep it simple: I would think that a user-selectable "timer" would be a relatively simple approach. Have the user decide how soon/often they want to be "nudged" back to reality. Whether it be by an explicit message, by a modification of game behavior, or whatever.