SFZero

"If there is such a thing as open source games, sf0 is a beautiful version of it."- Greg Niemeyer

From the site: "SFZero is a Collaborative Production Game. Players build characters by completing tasks for their groups and increasing their Score. The goals of play include meeting new people, exploring the city, and participating in non-consumer leisure activities.
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SFZero: An interface for San Francisco. That is to say, a new representation for the data that's already there. Your mind is full of /inaccurate/ representations that are affecting the way you use the San Francisco dataflow: steering you away from interaction and collaboration and towards unproductive reflexive data loops (forNext). SFZero designers are working double-shifts to engineer this next-generation interface that will bring you together with your cohabitants to experience the freedom that is /hard-coded/ into San Francisco's protocol."

http://sf0.org/