Why does it say 'Install' on the Autorun menu instead of 'Play'?

Why does it say "Install" on the Autorun menu instead of "Play"?I've already installed the game and played it twice.The only I can play it is by clicking on the Starcraft II icon.

Is it because it's still downloading patches while I play?Will I ever be able to play offline?


I should have known those alien maggots booby trapped this sub.