Bungie has released some new screenshots of a co-operative multiplayer mode called "Firefight" to be included in the Halo 3: ODST expansion pack, coming to Xbox 360 in September.

"Firefight will put you to the test as you and your friends assume the role of an ODST squad and fight together to take on increasingly challenging waves of enemies. It’s where new Halo heroes will be born, and an opportunity to step into the boots of a legend."

Also announced is a retail incentive whereby players will get a code to unlock Sgt. Johnson as a playable character in Firefight mode if they preorder the game. There's no word however on whether this will be available in New Zealand.