You might have noticed that many sci-fi stories feature violent future-sports, as if the XFL was a huge success and inspired imitators. Gears of War has Thrashball, Rollerball has itself, and Halo has the community-created Grifball. 343 Industries has decided to tip its hat to the game, by making it an official part of Halo 4's multiplayer offerings.
343 Industries announced the mode at its PAX panel over the weekend (via Eurogamer). The mode has players trying to get their ball to a goal, passing the ball like a grenade. You could have your masterful run cut short, though, if you're taken down with one of the two available weapons. A hammer will kill you instantly and send the ball flying out, while the short-range sword gives the ball to the one who scored the kill.
The panel also detailed some changes to the Capture the Flag mode. The flag-bearer has a little more agency in his or her own safety, since he can wield a magnum in the free hand or use the flagpole as a melee weapon.