The first “proper” release of Gnus 5 was done in November 1995 when it was included in the Emacs 19.30 distribution (132 (ding) Gnus releases plus 15 Gnus 5.0 releases).
In May 1996 the next Gnus generation (aka. “September Gnus” (after 99 releases)) was released under the name “Gnus 5.2” (40 releases).
On July 28th 1996 work on Red Gnus was begun, and it was released on January 25th 1997 (after 84 releases) as “Gnus 5.4” (67 releases).
On September 13th 1997, Quassia Gnus was started and lasted 37 releases. It was released as “Gnus 5.6” on March 8th 1998 (46 releases).
Gnus 5.6 begat Pterodactyl Gnus on August 29th 1998 and was released as “Gnus 5.8” (after 99 releases and a CVS repository) on December 3rd 1999.
On the 26th of October 2000, Oort Gnus was begun and was released as Gnus 5.10 on May 1st 2003 (24 releases).
On the January 4th 2004, No Gnus was begun.
Gnus 5.11 was bundled with GNU Emacs 22.1 in June 2007.
A version of No Gnus was released as Gnus 5.13 with GNU Emacs 23.1 in July 2009.
On April 19, 2010 Gnus development was moved to Git.
On the January 31th 2012, Ma Gnus was begun.
Since then, Gnus has only been released together with Emacs.
If you happen upon a version of Gnus that has a prefixed name—“(ding) Gnus”, “September Gnus”, “Red Gnus”, “Quassia Gnus”, “Pterodactyl Gnus”, “Oort Gnus”, “No Gnus”, “Ma Gnus”—don’t panic. Don’t let it know that you’re frightened. Back away. Slowly. Whatever you do, don’t run. Walk away, calmly, until you’re out of its reach. Find a proper released version of Gnus and snuggle up to that instead.