My BiL is a “white-hat” hacker and attends conventions, including gaming ones. The games are designed to be addictive.
These games, pretty much ALL computer games are designed as “Skinner boxes” which reward the players based on variable input - sort of like a rat hitting a lever. The payout has to be variable - if it becomes predictable, or is too low, the rat, er, player will eventually lose interest.
As are most games with varying degrees of attraction. I don't blame the game for his heart attack, he wasn't paying attention to his health. My friend had other things going on, involved in various organizations and charitable to others. He also chatted with other gamers world-wide through the game as an admin, dispensing help to others. However, he did play a lot at all hours of day and night.
I feel the addiction was the opportunity to play-act as other characters that he could not achieve in real life. In a game, you can have the looks and powers that you weren't given in real life. This is not necessarily a bad thing, and possibly brings fulfillment and happiness to many. The risk is getting so deep into the fictional characters that one neglects their external health and obligations. My friend was neglecting bills and getting into financial problems, this is something I feel was indirectly caused by the game.