I play it to get acquainted with the game's mechanics before jumping into multiplayer. None of the CoD games had story lines I can recall that well, but it's tradition that I beat them on veteran before jumping into multiplayer.
I would hate the FPS genre if it didn't have single player. It's just something to ease myself into multiplayer. It gives me a chance to learn to get a feel for the controls and find out which weapons do what and how they act. For me, it's preferable to joining a match full of five year veterans that kill you before you can even figure out which button lets you sprint. Day of Defeat has a ***** of a learning curve because of this reason. Even America's Army gave you a small tutorial before shipping you off to be killed in five seconds.
I would hate the FPS genre if it didn't have single player. It's just something to ease myself into multiplayer. It gives me a chance to learn to get a feel for the controls and find out which weapons do what and how they act. For me, it's preferable to joining a match full of five year veterans that kill you before you can even figure out which button lets you sprint. Day of Defeat has a ***** of a learning curve because of this reason. Even America's Army gave you a small tutorial before shipping you off to be killed in five seconds.