Come Out and Play: For kids, grown-ups

"I like the games that let grown-ups and kids play together," says Come Out and Play co-founder Catherine Herdlick. "I think it's really important for kids to see adults letting loose."

The festival of public games and activities, which starts Saturday in San Francisco, harnesses that childlike impulse to turn any park or public space into a playground via safe, kid-friendly - as well as adult-friendly - games devised by artists and game designers.

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