http://en.wikipedia.org/wiki/Gaming_...ible_diagnosis
Though video game addiction is not included as a diagnosis in either the DSM or the International Statistical Classification of Diseases and Related Health Problems, it is suggested that the symptoms of a video game addiction would be similar to that of other psychological addictions.[6] Like compulsive gambling, video game addiction is said to be an impulse control disorder.[7][8] While no diagnostic criteria have yet been established for video game addiction, the symptoms of impulse control disorder include regular or repetitive displays of at least five of the following:[9][10]
1. Persistent thoughts of the activity or performance of the activity.
2. Need for increased time spent on the activity to achieve satisfaction or diminished reward for the same amount of time spent on the activity.
3. Inability to control, stop or diminish the behavior.
4. Restlessness or irritability when prevented from partaking in the activity.
5. Lying to friends or family about extent of involvement with activity.
6. Committing illegal acts to sustain activity.
7. Relying on others to finance activity.
It's the last three items which really separate an "addiction" from the more innocuous "habit." IMO.