Halo 3: ODST is a shooter game with gameplay taking place from a first-person perspective. Although the gameplay of ODST bears a strong resemblance to previous Halo titles, the player does not assume the role of the enhanced human supersoldier Master Chief. Instead, the player controls a lone UNSC soldier in the city of New Mombasa, East African Protectorate (formerly Kenya). Since the soldier, known as an ODST or Orbital Drop Shock Trooper, does not possess Master Chief’s advanced armor, reflexes and strength, he is more vulnerable to gunfire; players are forced to act more cautiously. The soldier HUD is different from the previous series, with red outlines for the enemies, but the aiming reticle remains. While the game is not focused on stealth gameplay, some elements of stealth will be incorporated. It will also include an open world environment, utilizing the old vehicles and weapons, and adding new features like more varied acrobatics for the Banshee.
Set before Halo 3, the main objective of ODST is for the player to search through the ruins of New Mombasa and discover what happened to his missing teammates. As the player drops in the ODST pod, the Prophet of Regret’s ship is seen jumping into slipspace. After finding a piece of evidence left behind — a sniper rifle hanging on a lamppost, for example — a flashback is triggered and the player assumes the role of the missing soldier. After players find the first beacon, the choice of where to go next is up to the player. It will also include an option which, unlike other Halo games, will allow the player to play the campaign levels in any order they want to.
In a recent gameplay trailer, a game mode called Firefight is shown (see the 2nd video below), wherein players take on increasingly difficult waves of varied enemies, similar to Gears of War 2’s Horde mode. Firefight will include new medals as well as the ability to co-op with up to 4 teammates over Xbox LIVE or system link. Each player has a set number of lives which, upon their depletion the game ends. There is no time limit, no limited number of rounds and no maximum number of kills. Skulls will be incorporated into firefight as a means to increase the difficulty and provide variation. The maps used in firefight will be unlocked as the player progresses through the ODST campaign. It is also noted that the enemy characters appearing in each wave are generated at random, thus the player will be unable to anticipate the strength of the next wave prior to its arrival.