game rankings

The game rankings (#1, #2, etc) are based on users' ratings of the games, along with some extra votes (with mid-range values) added by the system so that a game with only one rating which is 10 will not automatically become the #1 game, and along with a secret algorithm to detect shill votes (e.g. fake user accounts created only to rate a beloved game 10, or a despised game 1).

There are zillions of forum threads where people ask why some game is #1, because they don't understand this. E.g. read:
http://www.boardgamegeek.com/thread/471921/agricola-and-puerto-rico-for-the-love-of-god-stop/