Capcom have released 3 new multiplayer modes for Resident Evil 6, exclusively just for Xbox360. Each of the modes can be purchased seperately (320 MSP) or brought as a bundle for a reduced price (720 MSP).

The new modes are:

Predator
In a series of quick fire rounds, up to six players take their turn as the fearsome Ustanak with full access to its weapons, while the others must avoid capture or worse. Human players score points for successful attacks, but lose points for being caught or taken down. The match is over once all have played as the Ustanak, with the participant with the most points crowned as the winner.

Survivors
This is the Resident Evil 6 take on the classic solo and team based deatchmatch mode. Like Predator, you'll compete for the highest score, but once a player is taken out, they respawn as one of the game's enemy characters, and must then defeat another human character in order to return to the fray as their original player character. Survivors is available for two to six players.

Onslaught
Chaining combos is the key to success in this two player mode where each must clear waves of oncoming enemies. The twist comes when a player completes a combo chain as this will send enemies over to their opponent's screen. Expect the balance of power to constantly shift in this intense addition to the Resident Evil 6 experience.

~ Source