Stable 29 was an experimental Stable which was not given an Overmare. Instead, it was given large numbers of robots and automation. In fact, it was run by a Crusader-class computer system, although this was not common knowledge. It is noted that many to all of the inhabitants were killed in various ways by failures of the automated systems, with some indication that Stable-Tec was to blame. Unlike most of the Stables which were occupied on the Last Day, Stable 29 was unique as it sealed its doors months before the Megaspell detonations, leaving the Stable Dwellers inside completely unaware of the fate outside.
Stable inhabitants came to believe that the killings (all noted events were fatal) were intentional acts by Stable-Tec. However, Littlepip discovered that the computer had been removing the weakest portions of the population in response to failures in the Water Talisman, until it had eventually killed everypony.
The Talisman began to fail; unable to produce enough water for the Stable's population. As the talisman could not be replaced or repaired the Crusader Maneframe reached a "logical" conclusion; if there was not enough water for the population, then reduce the population. The mainframe continued to reduce the population to meet the ever dwindling supply of water, until the water talisman broke completely. Since the supply of water was 0, the population was reduced to the same.
Shadowhorn was the engineer responsible for the computer system. She was killed while trying to repair it.
Stable 29 was also the place where Littlepip found Vinyl's memory orb about Pinkie Pie holding her last party and Twilight Sparkle having a falling out with her, along with Vinyls' record collection which was later given to Homage, the inheritor of the title of DJ-PON3 in the Equestrian Wasteland.
When Littlepip and her group visited the stable they initially found it to be quite peaceful. However the security systems were inadvertently reactivated by Littlepip when she attempted to use one of the faucets. After clearing out the security systems, Stable 29 was abandoned. Following the attack on Stable 2, the newly-christened Applejack Rangers setup a home base inside of Stable 29.