A brother and I used to play a lot of FPS online once upon a time and chat. We were both pretty good and could play around and experiment with different 'characters'. He is interested in similar thoughts as myself so we would discuss it and also observe others. Overtime playing with some familiar faces, we could know who they were before shooting them by the way they operated. People work on patterns and I think with enough data (backed up by controls) you could get a pretty clear picture of someone's personality. I wonder how much of the data from gaming is already matched up to social accounts...