Which SciFi ttrpg has the largest player base?

[Archpaladin Zousha]

I think part of the issue, at least as I see it, is that sci-fi games tend to rely more heavily on a particular setting or "brand" as central to their appeal: you're not playing a sci-fi game, you're playing a Star Wars game, or a Warhammer 40K game, or a Traveller game. You're coming as much for the franchise as you are for the roleplay experience.

Even more ostensibly generic games like Scum and Villainy not tied to a specific property have some specific worldbuilding that informs what stories it's trying to tell and what characters the players are incentivized to play. Beyond that, the only other sci-fi games I've encountered are space-themed hacks of generic game systems like FATE or Savage Worlds, often attempts to recreate a sci-fi property that doesn't have its own tabletop spinoff, like Mass Effect or something, and then of course there's the inevitable attempt to twist and cram a homebrew sci-fi setting into D&D's ruleset.

It's a lot easier for a game to speak in generalities with a fantasy setting for an RPG, but from my observation people's expectations are higher for sci-fi. Like, if games were ice cream, fantasy is vanilla, but in scifi's case there's things like rocky road and neapolitan and there's even mint chocolate chip and cookies and cream but no one orders just plain chocolate, if that analogy makes sense.