In one of my late night musings, I asked myself, "Self, what would happen if gravity pulled us up towards the sky instead of down towards the ground?" and being a volleyball player, I wondered how that would affect the game. So let's create a situation to isolate some factors to get a better idea of what some possible outcomes would be. Let's say that, for this scenario, the court is the only area affected by the change in gravity. So the fans in the bleachers are seated and the coaches, players and refs on the sidelines are all able to stand like we do today. Pretty high tech court I'd say. So it would probably start off with a bunch of players on the ceiling. When the ball was served you would have a very hard time getting the ball to reach the other side because gravity would pull it up into the ceiling. Say someone did manage to get their serve over the net (which is still on the ground), once the ball gets to a hitter, they would have to hit with a much larger force to get a kill. Their arm swing would have to be greater than the force of gravity pulling on the ball. If the forces are unbalanced and the force from the hitter is larger that the force of gravity, the ball would be able to reach the floor of the court.
The likelihood of anyone ever attempting to try this is probably very low due to the fact that it would make the game about 10000 times harder unless they changed some more variables of the scenario. It's an interesting idea to consider though, how a change in the direction of gravity would affect our daily lives. Especially when some variables of life are kept the same.