NOTE: I am not trying to bash this franchise or anything. I am just trying to satisfy my own curiosity.
Why do people keep buying Call of Duty games? They are decent games, but what makes all of you come back to this franchise, year after year? After all, it's not like there are that many changes made from one game to the next.
This is an experiment of sorts. Can anyone here give me a concise answer as to why this series sells as well as it does?