I never said they made the entire fallout series. I said that they were known for making games in the fallout series. They have actually made two games for it, Fallout 3 and Fallout: New Vegas. If you were to say "Bethesda", fallout and the Elder scrolls would be the two game series that immediately come to mind, thus, it is what they are "known for". If you want to get nit-picky about it, Bethesda actually flat out owns the Fallout IP now, so it technically owns all past and future fallout games as well.