Obviously, some liberties have to be taken with a sci-fi game/story because many of the technologies sci-fi authors present don't CURRENTLY exist. However, some "sci-fi" contains technology that could plausibly exist someday in the future, and other types of sci-fi might more accurately be described as "science fantasy" because they contain many technologies that are obviously not plausible.

Some examples of each:

Science fiction: Star Trek (warp drive and directed energy weapons are plausible -- see the Alcubierre drive concept for example)
Science fantasy: Star Wars (not plausible: the force, lightsabers)

Some might argue many Star Trek technologies are unlikely to ever exist, and in some specific cases (the Q for example) you could probably make compelling arguments that is the case. But I think the point is that some sci-fi makes a bit more of an attempt to write a more plausible story, and others just go charging ahead with the most extremely implausible fantasies while showing a complete lack of concern for whether the story is even remotely plausible.

Which variety of "sci-fi" does this game belong to? Does it at least attempt to be somewhat realistic?

I think it is a bit of both. There are a lot of concepts incorporated that already exist today and some that may be available in the not too far future. Most of the tech tree is rooted in reality: https://guides.gamepressure.com/surviving_mars_guide/guide.asp?ID=43930
For the sake of playability things have to be simplified and streamlined, but that is also the case in any other building simulation.
Some of the mysteries lean more towards fantasy, but that is okay for me. There have to be some surprises. :)

Also, much of the overall look of the game is borrowed and pasted over from the very optimistic view of the future from the sixities (like "The Jetsons" or the depictions of future tech on book covers). This might not be accurate from a scientific point of view, but I like this retro-futuristic touch very much. :)