8. Grand Theft Auto
Here's a video game so addictive that people didn't just book holiday time off work to play it; people flat out didn't go work the day that Grand Theft Auto IV was released, with bean-counters suspecting that the suspiciously high number of sickies actually impacted the UK's economy somewhat. Why is the GTA series so addictive? Ever since the first game, for even casual players, the appeal hasn't so much been completing the story-based missions - which have admittedly become more ambitious and impressive with each passing installment - but the free-roaming nature of this sandbox world, in which all manner of mayhem is possible. Go into a gunshop, buy some guns - or if you're lazy, use a cheat - and start lighting people up. Steal a car, get chased by the cops, blow the cops up, get chased by a SWAT team, and then probably explode in a fireball. The sheer mania of the city is what makes it so enjoyable to waste hours just interacting with it; even just cruising around, trying not to break the law, is a fun, relaxing exercise in of itself. No doubt, when GTA V finally hits stores this September, we'll be infatuated with our old friend all over again.