I read somewhere that Titanfall incorporates story into the actual multiplayer mode. I'll try to find the quote as I write this post.
Here it is:
"The game is online multiplayer-only, but injects single-player elements such as plot, character chatter, and non-player characters into its matches. Bit-tech reported the game to have 15 maps, 33 weapons, and splitscreen support for the online multiplayer, though the developer had previously denied the latter. Respawn founder Vince Zampella described the game as bringing "scale, verticality, and story" to first-person shooter multiplayer gaming."
I wouldn't view Titanfall as merely an "online multiplayer shooter" only, because that isn't the way it was made. They made it multiplayer so there's constant challenge from other players, but they've integrated elements from a single-player game. I'm getting an Xbox One sometime next week (or this weekend, if I'm lucky) and I'll be playing it then. Just for now, I've been watching videos and the game honestly does look spectacular and exciting to play.