If you an average male into video games it's going to shill you popular video games. That's an assumption given your gender and age and probably location and most of the time it's a correct choice. It's not as advanced as you think it is.

It's not really all that crazy to think though. We create categories for people in our own heads and predict their behavior all the time. Often times we get it right because people are at least somewhat predictable. Look no further than starter pack memes.