The Single Pony Project, later renamed to the Single Pegasus Project, was a pre-war project developed by the Ministry of Awesome. The Project was often shortened down/abbreviated to S.P.P.
-MASSIVE SPOILERS ALERT-
The Single Pony Project had its roots in the war effort that started with the pegasi, considering they were one of Equestria's key wartime assets during the war. They provided Equestria with unprecidented aerial superiority against their zebra foes. The pegasus ponies were also required to regulate and control the weather and played crucial roles in the changing seasons, like at Winter Wrap up.
Rainbow Dash and her ministry devised a way for the skies to be controlled, freeing up the pegasi and allowing them to participate in the war effort fully. The plan was christened the Single Pony Project which would allow a single pony to control Equestria's weather.
During the WarEdit
Throughout the war, towers were built around Equestria and linked together at Neighvarro, where the S.P.P's control tower was located. Rainbow Dash had a Crusader Maneframe specifically made for the tower to help the pony controlling it to manage and regulate weather across the entire country. The S.P.P was completed during the war, requiring Rainbow Dash or another pony of significant rank like another Ministry Mare or the Princesses to be fully activated and accessed.
The Last DayEdit
During the Last Day, the S.P.P could not be fully utilized since Rainbow Dash refused to help the Pegasus goverment/ early Enclave and turn her back on the rest of Equestria. The Enclave hired Gilda to kill Rainbow Dash and bring back her head so they could gain access to the control tower. Celestia managed to make her way into the control tower and downloaded her mind into the Crusader Maneframe inside the Tower, and turning it into a Soul Jar, hoping to prevent the Enclave from closing up the skies and covering Equestria in constant cloud cover.
The Enclave cannot fully utilize the tower to its full potential but can use it to a limited degree to cover Equestria in constant cloud cover and farm fresh food using cloud seeding around the S.P.P towers. This also forces the Enclave to keep their population at a certain size to prevent overpopulation and starvation. One of the S.P.P Towers was destroyed by Homage when the Enclave began attacking the surface. The tower was destroyed by causing her Star Blaster to self destruct.
Littlepip, at the end of her journey, managed to reach the interior of the S.P.P, which is partially controlled by Celestia and entered the stasis pod, taking control of Equestria's skies for the present and forseeable future.