I'd never heard the term ludonarrative dissonance before, but in the last day or two I've come across it several times. It seems to be basically the idea that in a video game the story written by the designers is often in direct conflict with the actual mechanics of gameplay. Two examples: In Uncharted 2, the cutscenes depict your character Nathan Drake as an easygoing, good-humored dude, but the actual gameplay involves Drake ruthlessly killing over three hundred people. The Drake of the cutscenes doesn't seem like the sort of person who could kill so many people with so little hesitation, or be so nonchalant about it afterward. Also, in Shadow Complex the cutscenes tell you that goons are taking your girlfriend to a helicopter and that you have to rush over there to save her, but in the actual game you spend a lot of your time scouring every last nook and cranny looking for power-ups.