What about alien or space type of game can recommend me?
Future Fragments has some alien stuff, but it's not a huge proportion of the content; Xenotake I mentioned already...
Ass Effect, Lust Affect, and The Pilgrimage are all Mass Effect parodies that are very fun, and while they each have very different art styles, they all more or less cover the same range of fetishes that show up here.
Arenus I haven't personally played much of, but it's a game by the Roundscape Adorevia people (also the group who did Ass Effect above) in an original space opera setting.
Behind the Dune I likewise haven't personally played much of, but I've heard good things. A Dune parody, in case the name didn't give it away.
Mercanoid and Trials in Tainted Space are both text-based games that prominently include furry content, but they're both good sci-fi porn.
--Below this line we're moving farther away from either the type of game we're looking at or from the fetishes involved, or both
Perky Little Things is overall a different kind of content, but it does include at least one sci-fi level
Run Construct Doting is a Jack Cayless visual novel in a sci-fi setting
Space Corps XXX is slower, and has a much wider range of fetishes, but it's another one that's good sci-fi porn
Tactics Elemental is slow to play but not bad; the porn can sometimes feel like an afterthought, but I'll mention it anyway
And Third Crisis is the only entry I'm putting here that doesn't have any space opera content, but it is still sci-fi in that it takes place on an alternate high-tech future Earth. It's a loose Overwatch parody (though with a largely original story) starring a Tracer knockoff, and covers a lot of the same fetishes that appear here, albeit with a female protagonist.
Also, actually, you know what, it isn't porn, but I'll also list the white chamber (non-capitalization intentional), since you didn't technically specify porn, just alien/space-themed stuff. It's a sci-fi/horror game set aboard an empty spaceship and starring a very hot punk girl, though, again, not pornographic or otherwise sexually explicit in any way.