Here is a link to a government pamphlet on drug addiction that has a very clear explanation of how addiction affects the brain. There is a downloadable pdf file. I know it's about drug addiction, but, given the research on dopamine release during video game playing, it's a good explanation for how gaming addiction works too. Obviously, much more study needs to be done, but this explains it clearly for the lay person.
"Small service is true service while it lasts. Of humblest friends, bright creature! scorn not one
The daisy, by the shadow that it casts,
Protects the lingering dewdrop from the sun." -------William Wordsworth