First post, so, hi!
Have to go with the sci-fi/futuristic option, though I'd like to say that I like "realistic" or plausible science-fiction the most, hard sci-fi. It's very hard to find though, right now only Fallout comes to mind and maybe Bioforge (haven't finished it, but what I saw, seemed to fit). Oh, and Beneath a Steel Sky, of course.
Also I don't consider space opera sci-fi, it's more like fantasy in space, as it doesn't explain the science, things just work.
EDIT: Forgot another one or two rather Policenauts and Snatcher