Twinity is a 3D online virtual world. Initially developed by Metaversum GmbH, it is currently held by ExitReality. The game offers its population, called Twinizens, to navigate around virtual (historical) versions of real-world cities, also called a mirror world or a Metaverse. A public beta began in September 2008 with the release of the first virtual city, Berlin, which later was followed by Singapore, London, Miami and New York. Twinity is built on BigWorld Technology and its economy is based on a free-to-play model.