Okay, so now you have real characters, you need to put them in real worlds. A lot of this is questioning your assumptions.
We all know about questioning your PHYSICAL assumptions. If you don’t know about it, please go and read about the geological past of the Earth. There might be such a thing as “tropical planet” — in the real warm cycles, most of the earth was sort of warm, and the colder areas were temperate — but the Earth has never been a ball of ice, while inhabitted by humans. There will always be warmer zones. Water planets… I don’t know. I suppose doable, but again, in general, no world is the same thing all over. Remember that.
Which brings us to the important part: no world is the same thing all over.
And here I must confess The Brave and The Free (which I’ll really finish this year) is set in a totalitarian Earth, but since most humans have gone to space, the POPULATION of that Earth is about that of a small European country. Maybe ten million.
The fact is that 1984 was never very believable. If you want to imagine how not, drop JUST ONE individualist and resourceful character in there, and watch it shatter. It only works because the main character is a depressive like the author, and all the other characters are reflections.
This was the biggest flaw with the “one world governments” of the golden age. They had no clue how different other cultures were. They THOUGHT they’d remade Japan and Germany and could do it to everyone. (It wasn’t as advertised after all.)
So, first check for characters. Remember if you have a whole world, you’ll have cultures and people who are nothing like yours and you. Then examine it for “it’s all the same thing.” Heinlein did this well in If This Goes On, in which Mexico — MEXICO — is a haven of freedom, even as the US loses its mind. At that, I think he was too… optimistic? Pessimistic? about the US being all the same thing. It’s never that way, and there would be regions were deviationists were the majority.
Look, the USSR was UNDONE by typewriters. Not even photocopiers. Typewriters. Anything with more tech than that, will have trouble with the “wholly totalitarian” unless there’s a biological or cultural reason. (China tends more towards the totalitarian than anywhere in the west, because of long and brutal history and the culture that shaped itself to it.)
If you absolutely must have totalitarianism over an ENTIRE area, please make it short time or give us extraordinary reasons for it.
Okay. I need more coffee.
Next week: hanging a lantern on it.