SAN FRANCISCO (AP) — In a sea of virtual-reality headsets and monitors broadcasting video games, there's something that seems completely alien at the Game Developers Conference: a swing set. The piece of playground equipment has been plopped down inside San Francisco's cavernous Moscone Center to promote Biba, an upcoming app that seeks to stop children from transforming into touchscreen zombies. "The idea behind it is to simply get kids outside playing using devices and systems they're already familiar with, like touchscreens, phones, that kind of thing," said Biba chairman Greg Zeschuk while a pair of adult conference attendees giggled and glided on the rope swing next to him. The app is designed to be "playground agnostic," meaning parents tell Biba what equipment is available, and it provides compatible challenges for youngsters.