The Come Out & Play Festival is a street games festival dedicated to exploring new styles of games and play. It was held last weekend (September 22-24) on the streets (and even on the buildings) of New York City.

Some of the interesting games include Space Invaders (giant game of Space Invaders on the side of a building, with your body as the controller), Identity (large-scale social game of secret organizations, covert intelligence, suspicion, trust, cooperation and betrayal), Snagu (camera-phone based scavenger hunt with no limits on time, space, or answers), Manhattan MEGAputt (gigantic game of mini golf, played in Manhattan’s East Village), Cruel 2 B Kind (benevolent assassins stalk New York performing acts of kindness for strangers in an attempt to catch their prey), and Payphone Warriors (control city turf by capturing the city’s payphones).

CNET has pretty good coverage of the event:

• Gaming on the streets of Manhattan
• 'Payphone Warriors' call on New York streets
• 'Killing' gamers with kindness

The last couple of articles go into more detail about specific games. Sounds like it was a lot of fun.