Popularity is a number of factors: views, downloads, and when the game is released are part of it. I don't want to reveal all the specifics so people don't try to game it. I have some plans to improve the algorithm a bit, I want to make it easier for new things to get to the top. The problem right now is that if games are really popular then they tend to get stuck at the top, and that prevents new stuff from surfacing.
Visits to your own game pages do not count against your total view count.