I would say that movies are a bit shoddy as a grenre because you can always mix certain styles, a TV series even more so, particularly when you take something as Doctor Who that has been runing for decades, I guess? But even with movies you have something that is called a
tone which you have to follow, or you will get something completely different. If you make a love story with action inside or an action movie with a love story inside matters a lot, see the difference between Titanic and Indiana Jones. Changing that tone can give you
very different results, like as if someone got the idea to write Terminator 1 as pure love story. And I doubt someone would ever see Titanic as a Sequel to Jaws I guess. - Extra bonus,
Batman Begins ... as comedy.
So while you have some freedom with movies, even here you don't get a free pass to do and mix everything as you please, unless you REALLY know what you're doing! What people often don't see is that every craft really, even one that is so full of creativity follows certain principles, and it is best to follow those, like movie making 101. That is why there are schools for writing, movie making, design etc, because they do REALLY teach you someting. That is why you set a tone and stay true to it for the most part of the movie, or it will just lead to confusion, like having comedic slap stick scenes next to very dark, realistic and depressing ones. Not following those rules requires an very exceptional kind of character, like David Lynch or Jodorowsky for example. If you do not follow those principle and you're not one of those exceptional individuals ... than you get something that is as trash like the Star Wars prequels. Because as good as a buisness man Lucas might be, but he is a shitty script writer.
Thing is, when you have a game like Fallout 1 that can be still played and directly compared with new instalements, with looking up developer quotes, development documents and design principles that have been set in pre-production you can very easily identify what Fallout was about.
And it doesn't take rocket science to do that. Remember, we are NOT talking about taste or quality here! Just comparing design principles. And it is pretty obvious that both Bethesda and the team behind Fallout 1 follow very different design principles and goals.