Le Parkour / Combat Parkour: Something of a standard part of the skillset, even for getting around normally, in the modern era. This tends to come from three places: one, common exposure to how one gets around in microgravity; two, lots of habitats and inhabited planets/moons having less than “standard” gravity anyway, making it easier; and three, lots and lots of biotech work pushing the baseline on agility, reflexes and stamina well above where they used to be. Couple that with the circular feedback effect of architectural adaptation, and there you go.
In its combat form, a specialty of light legionaries. (Not so much one of heavy legionaries, since the problem with trying this while running around in three tonnes of combat exoskeleton isn’t that you can’t do it, it’s that the walls can’t take it.) It did not take much exposure to space-based infantry combat for people to figure out that – especially when fighting people used to operating in two dimensions, but hardly limited to that scenario – a chap who can run on walls, change orientation and vector in mid-air, and make use of all the bits of the environment, not just the floor-based ones, and so forth, has a distinct advantage. Enter, then, the trainers and armor designers figuring out how to do all that stuff down t’well, too.