I never said that.
It wasn't renamed. Gurps was dropped and a new system was created and coded in just two weeks in the third year of development( ref:Tim Cain ), which I believe was the last year.
Funny, when creating Fallout 1, the engine was made first. For the first 6 month there was one programmer and he was working solely on the engine. Without that person the game would not exist. Then the whole concept and story was constructed gradually. The rules were actually made in the last...