Both of the bombs dropped on Japan during World War 2 had their own codenames. One was called Fat Man, while the other was known as Little Boy. Fallout players should recognize these names.
Nagasaki was not the intended target for the atomic bomb delivery. Instead, the city of Kokura was supposed to be destroyed, but a low-flying cloud blocked the munitions plant that had been the target. The bomber was required to drop on visual identification only.