Orion's Arm

Orion's Arm (also called the Orion's Arm Universe Project, OAUP, or simply OA) is a multi-authored online hard science fiction world-building project, first established in 2000 by M. Alan Kazlev, Donna Malcolm Hirsekorn, Bernd Helfert and Anders Sandberg and further co-authored by many people since. Anyone can contribute articles, stories, artwork, or music to the website. A large mailing list exists, in which members debate aspects of the world they are creating, discussing additions, modifications, issues arising, and work to be done.

A computer game and a tabletop role-playing game are being developed by the community, within the OA milieu. There is an ezine for Orion's Arm fiction, art, and commentary, called Voices: Future Tense, add-ons for the Celestia program to displaying Orion's Arm planets, spacecraft and other objects, and additional transhumanist flavored SF illustrations.

The first published Orion's Arm book, a collection of five novellas set within the OA universe, called Against a Diamond Sky, was released in September 2009 by Outskirts Press. The second published Orion's Arm book, called After Tranquility, was released in February 2014.