From Halopedia, the Halo wiki
Gravball is available on some schools' playgrounds. As a child on Eridanus II, John-117 was not allowed by the other children in Elysium City Primary Education Facility Number 119 to play the game because he always won. Bars, such as the officers' club in the UNSC Recreational Facility 6055-NA-A, often feature screens displaying gravball matches for the patrons' entertainment.
Ricochet is a variant of gravball used for training by UNSC drill instructors. Likened to "combat basketball", Ricochet combines combat simulations with the gameplay of traditional gravball. The Spartan-IV complement aboard the UNSC Infinity recently incorporated Ricochet into the ship's training decks as part of their War Games exercises.
Under the rules of Infinity War Games, Ricochet players earn 20 points for throwing the ball into the enemy's goal and 50 points for running it in. The first team to 150 points wins. It is unknown whether these rules apply to regular gravball.
List of appearances