Given I know of no way of responding directly to Astronaut Reisman's request for space sports ideas, I will respond in this public forum.

SPACEBALL: A two person ball game in space.
Spaceball is played with a nerf ball (or other ball that has little inertia that could damage anything).Two people are separated over an "not completely determined what's best" distance (let's say 10ft or 3m). It would be nice to have boundaries marked with some sort of (laser?) light screen but some hull markers(colored strings?) could do if you lacked the better option.

Legal hits are limited to the following set of body parts (variations: could be extended with your imagination) knees, feet, elbows, hands, and forehead. Any given "point" has a server and returner. The server initiates a point by striking the ball legally towards the other players boundary. The ball must be hit and not grasped. The player opposing the server is designated the returner.

The server and returner must hit the ball from behind their respective boundaries. A returner must hit the ball with the same body part that was used by the server. When and if the ball returns back to the server, the server has the option of returning the ball with a any of the legal body parts. But the returner must always use the same body part that the server uses. If either a returner or server fails make a legal hit that crosses the opponents boundary (without hitting a wall), then a point is scored to the opponent.

Really the game could be played to any of the sets of rules for scoring points and changing serves, of other popular games like table tennis, volleyball, tennis, or other racket sports. And how many points to win a game, games to win a "set" or sets to win a match, could be also be determined by any of those. Initially, I would try rules of table tennis. Server has 5 consecutive serves before switching to returner. Games are first to 21 with a separation of at least 2 pts. A set could be best 3 out of 5. How many sets could be optional and determined by how much time you have to play.

Two major variations of the game could be whether you allow the players to have any contact with surfaces. With the no contact rule, from the point that an opponent strikes a ball towards a players boundary until the player returns the ball, there can be no contact with walls or other surfaces by the prospective returnee. The striker after hitting the ball, until the returnee hits the ball may have contact (to restabilize). I think the no contact rule should be the base rule, and allowing contact a (beginner) variation of the game.

Other areas of potential variations are the distance between opponents, and the shape and size of the planar barrier that must be crossed by the ball (is it situated some distance from the walls or does it extend all the way to a wall). There could also be a "doubles" or even "triples" version, with subs entering the playing field during the "stabilization" period.