Which SciFi ttrpg has the largest player base?

[Batcathat]

I mean, the reason for that assumption is because Dungeons and Dragons has been around so long, and cast such a wide shadow, that most gamers just default to it, regardless of specifics. Forgotten Realms, over the years, has tried to cram all those different styles you mentioned in to the same setting, and it's only become more pronounced as FR became the primary D&D setting through sheer inertia. And Pathfinder did the same thing with Golarion. When people say "Fantasy RPG," most of the time what they mean is "Dungeons and Dragons," and what I'm trying to say is that there isn't really a "Dungeons and Dragons" tier sci-fi RPG, though Lord knows Starfinder is TRYING to be that...

It's interesting to note that this situation is basically a mirror of fantasy and sci-fi as a whole, where Lord of the Rings is still basically the fantasy novel to the point that having elves and dwarves is basically considered the default. Meanwhile, there are some big sci-fi franchises (Star Wars¹, Star Trek, etc.) but none with the sheer influence on the genre that LotR has, I think.

(¹ Let's not get into the whole "Is Star Wars sci-fi or fantasy?" discussion right now)