Wikipedia
UnaXcess is a bulletin board system originally started by Brandon S. Allbery in 1984. During 1989-1990 it was taken up at and rewritten at Bradford University. During the early 1990s it moved to the University of Manchester and was used for several years, mostly by members of the Computer Science department.
Around about 1998, work started on a re-write of the code base overhaul the current system whilst keeping the quirky aspects that many users had grown to know and love (such as pressing 'G' to quit). By September 1999, the new system was ready to be rolled out.
Today the system is known as UA2 to most people and is mainly haunted by current and ex students from the University of Manchester Computer Science department and members of its computer society, CompSoc. As well as the familiar telnet interface, there is also a web-based version of the client (uaHTTP) that is more friendly to beginners.
The code for UNaXcess (client and server) is available for free download.