Super Mario Galaxy is the spaciest space game of all time.
To be fair, it doesn’t seem that way at first glance. Mario is a plumber from Brooklyn by way of the Mushroom Kingdom, which isn’t the kind of CV you need to get into NASA. The planets have nonsensical and inconsistent gravity, the stars have big cartoon eyes and goofy singsong dialogue, and all of outer space is ruled over by an amazonian princess with a magic wand. But, beyond all the parts of Mario Galaxy’s space that put it squarely in the Disney afternoon sector of the universe, its mechanics are not only what make it unique among platformers, but the only game I can think of that’s both about space, and actually feels like it earns it.
Years ago, Nintendo used to hold a show called Space World. It was a sort of Nintendo-only counterpart to Tokyo Game Show, which they didn't (and still don't) attend, where they'd announce new games and consoles, and put them out for the public to play. It had very little to do with space as a concept, but its makes for a very convenient segue into the fact that Nintendo has a crazy shared universe you never knew about, and it all takes place in space. Also, it's all perfectly reasonable and requires no insane leaps in fan fiction logic.
For any number of reasons, games set in space form the backbone of our medium. For the most part, they feature the kinds of narratives you'd find in a YA book with a cool space dragon on the cover, but sometimes, they strive to be a little more. Some games take that concept of space, which most people have never really interacted with, and finding the ways it intersects with a primarily interactive medium. Which is to say, sometimes games are about big, empty voids, and sometimes, they like to contemplate infinity, and maybe even mechanize it.