Metaplace, closed alpha September 2007

See also link

Metaplace is a software platform that democratizes the development of virtual worlds. The platform is developed by Areae, the company established by Ultima Online and Star Wars Galaxies designer Raph Koster. According to the official website, the platform is "client-agnostic", which means that virtual worlds developed on Metaplace can be accessed using any device that connects to the Web. Source: link