"It'd almost have to,' says Tim. "They're prone to centralization. The Combine here would lose touch with their command immediately if that happened."

Shephard, for his part, is examining the map and scowling. "This was a real city once," he mutters. "Had a water supply, right?"

"Beg pardon?"

"Back when humans lived there, Pittsburgh had sewers," says Shephard. "Unless they've got somethin' guarding the pipes from the inside, that's God's own way of sayin' 'here, I want this place undermined'. If there's a way into the Scab from below it'd make getting in on the surface a whole fuck of a lot easier."