What is blitz ball? Who creates this and makes up the rules?

Phineas created the game of Blitzball. The game has no teams, and the odds are against the player carrying the ball. The ball carrier has to outrun everyone else playing or give up the ball to another player. Players have the right to refuse to carry the ball.

“Stop, stop!” cried Finny in a referee’s tone. Everybody halted, and Finny retrieved the ball; he talked better holding it. “Now Leper has just brought out a really important fine point of the game. The receiver can refuse a pass if he happens to choose to. Since we’re all enemies, we can and will turn on each other all the time. We call that the Lepellier Refusal.” We all nodded without speaking. “Here, Gene, the ball is of course still yours.”

Now if you are refused three times in the course of running from the tower to the river, you go all the way back to the tower and start over. Naturally.”