Construction and Purpose
Vault 99 began construction in the Summer of 2068. It was built in a newly-annexed Canada. During the construction process, Canadian citizens unsuccessfully attempted to sabotage it.
Vault 99 was given no prepackaged food or food synthesizers, and was designed as a test of ingenuity as to keeping their existing food sources - twenty cows, thirty pigs, and one hundred hens, and a mule - going.
The food supply of Vault 99 was quickly diminished. Those that inhabited the Vault slaughtered the animals they were given within the first few years, though a few attempts to breed them instead were made.
Without food, the Vault Dwellers had two options - starve, or eat one another. Those who refused to dine on the flesh of their fellow man tended to become food of others. This only lasted so long, however. The population of the Vault quickly dwindled, and those few who remained fought amongst one another for the last bits of flesh, by this time no more than raving lunatics.