I was just contemplating the idea of sports played in microgravity or low gravity by human beings. But I think humans would have trouble with 3D sports. Our mindset is very often linear. Or planar--two practical dimensions, width and depth, that's how we think. It seems to me that most humans would get confused in playing a truly three dimensional game.
While its true that there are humans who pilot aircraft in the three dimensions of the atmosphere and other humans dive in the ocean, managing to do well enough in liquid three dimensions to get by, my sense is true mastery of three dimensional movement is something human beings are not especially good at. Even aircraft combat tactics tend to find planes to fight in from what I've read on the topic (though this is in part because airplanes don't move in all directions with equal ease).
So what if in the future humans finally discover how to communicate well with dolphins and enlist dolphins as fighter pilots in combat spacecraft? Or as interstellar navigators? Dolphins deal with three dimensional movement every day of their lives and probably do a lot better job of it that a human being could ever naturally do.
Note that what I'm suggesting does not require dolphins to be fully as intelligent as humans overall. My speculative idea in fact only considers dolphins superior in mastery of motion in 3D. Though in a story setting one could imagine they are as smart or smarter even in every way. Or alternatively that their spatial motion ability is their only special mental trick. For the record, I don't believe dolphins are as fully intelligent as humans, but that wouldn't stop me from using this idea for a story.
Perhaps instead a story could feature a human-dolphin hybrid, able to use language the way human beings do (and perhaps also with human aggressiveness), but every bit as much a master of all three spatial dimensions of the universe we ordinarily experience. I wonder what such a hybrid would look like? And how would such a creature be produced in the first place? And by whom?
If I were to use the phrase "Dolphins in space," that might sound like a corny science fiction movie from the 50s. But dolphins have in fact been featured in serious science fiction stories by writers as well-known as Larry Niven and Anne McCaffrey. But this particular angle, the mastery of three dimensions being the primary reason dolphins would be in space, has not been focused on in science fiction to my knowledge...