SARCHA (School of ARCHitecture for All) www.sarcha.gr not-for-profit founded in 2006 in Athens; it is an expanding open structure with currently 215 associates of various backgrounds in different countries. It has initiated international research programmes which contributed to systematizing city problems such as, the potential of the ‘un-built’ condition and its relation to the category of the ‘public’, the impact of immigration onto the city, the rethinking of the city as a pool of resources to be administered ‘in common’, and the city of Athens as experienced by its youth. SARCHA‘s work has been shortlisted at “The Resourceful Architect” competition (the Royal Society of Arts, and the Architecture Foundation, London 2011). The current work on Polypolis uses a social game that reverses the logic of 'monopoly' of 'one winner takes all', adapts it specifically to the complex issues facing contemporary cities and experiments with different ways in which the common resources of the city can be held and mobilised in common by its inhabitants.