Communist, i.e. total state control of all means of production
Please don't forget the fascists here. Nazi Germany was every bit as totalitarian as the Stalinist USSR, they just had different strategies for managing the national economy.
In most science fiction settings, mega-corporations are very powerful, and rival, or even exceed the power of governments. I'd like to see a game with mega-corporations.
Lapsed anarchists like me love this sort of question.
Depending on who you adopt as an intellectual authority, SF "mega-corporations" like this *are* governments--they are oligarchies, most often with an authoritarian streak. The have total control over the lives of huge populations, sometimes whole planets or more. The only difference between them and what most US citizens mean when they say "government" is that there is typically *no* input from rank and file employees.
OTH, Bruce Sterling's novel
Islands in the Net does offer some interesting exploration of the idea of a democratically operated corporation operating in a larger world along the lines Blackrook mentions.