Firefight

Firefight is a single/cooperative campaign mode for Halo 3: ODST where up to four players can participate with one another via System Link or Xbox LIVE and combat against the Covenant. According to Bungie's Halo 3: ODST project page, the mode allows four teammates to "battle in multiple environments, on foot or in vehicles, and against increasingly difficult waves of Covenant attackers." Firefight will have no limit on the waves of enemies and will continue until the squad has completely run out of lives, however there are five waves in a Round and three rounds in a Set. The Set, Round, and Wave the player is in can be seen at the top left of the screen, with the number of players lives. The Set number is represented by a number 1-3, the Round will be represented by a circle, going from left to right with the wave the player is in shown under the Round. At the end of the round there will be a brief pause where the player will be allowed to recollect ammo, and get additional lives. The scores will be kept in the top right of the screen, with the Team score being on the top and the player's individual score below that. Regardless of the difficulty, the Tough Luck skull will be enabled from the start. With each new set, more skulls become enabled, more than one at a time. If you can stay alive, they will be awarded with higher scores and heaps of medals. Though each enemy class is worth a base number of points, earning medals can modify the player's tally as they go. Staying on lengthy streak without dying, and points will be augmented by a hefty multiplier.

Also, according to the ODST project page, players who pre-order the game at Gamestop will be able to play as Sergeant Johnson in this mode.

Players are allowed to customize their armor, emblem, background and Service Tag much like in Halo 3 multiplayer.

Trivia

 * Firefight might play out like Survival Mode from the Marathon games which also involved fighting seemingly endless waves of enemies until the player dies.
 * It is similar to Call of Duty: World at War's Nazi Zombies mode and Left 4 Dead's Survival mode.
 * The player will be able to choose from four skulls at the start: Blind, Cowbell, the Grunt Birthday Skull, and IWHBYD, their effects are the same as in Halo 3. The skulls can be seen at the left side of the screen, the ones active will be highlighted.