We've seen quite a bit of protagonists Joel and Ellie in The Last of Us, but haven't heard how the two leads got together. Naughty Dog's game director Bruce Straley and creative director Neil Druckmann have explained some of the back story that sets the game's events in motion, including how Joel came to take care of Ellie.

Despite the title, the two aren't the last survivors. In fact, they both live in one of the last quarantine zones operated by the military, Druckmann explained in a Game Informer interview. Since Joel has been alive since before the outbreak, he's experienced loss and become a harder man for it. When the game starts, he's willing to compromise some principles, and he works in the black market. He's given a job to smuggle a trouble-making 14-year-old girl, Ellie, out of the quarantine.

The reason Ellie needs to be smuggled out is being kept under wraps, but things don't go according to plan. Before long Joel is stuck outside the quarantine zone with her, and he can't reenter because the military would hunt him down. So he accompanies Ellie to keep her safe, to deliver her to a contact.

Outside the quarantine, the environment is a destroyed, overgrown cityscape. The team says they were inspired by the book The World Without Us and "ruin porn" photos of urban areas where nature is intruding. "We're constantly pushing nature back to not reclaim the cities," Druckmann said. "In New York City, they're constantly pumping water out. If electricity ever goes out, within two days the subways are completely flooded. Water comes in, and structural integrity starts collapsing and falling apart, and nature starts coming in."

The Last of Us will be available for PS3. No release window has been set.