Medal of dishonour: why do so many people cheat in online video games?

The idea of bending the rules has been part of gaming culture from the start. Even the simplest, most light-hearted games have players using hacks to improve their performance, something that utterly ruins everyone else's experience. Why has online cheating become an infestation? Keith Stuart explores some of the hypotheses that trace the roots of this chronic behaviour all the way to our own self-esteem.