What is halo odst about?

Answer 1

Set during the events of Halo 2 and before Halo 3, the main objective of Halo 3 ODST is for the player to search through the ruins of New Mombasa and discover what happened to his missing squad mates. As the player drops in an ODST drop pod, the Prophet of Regret's ship is seen jumping into slipspace(like the ending of Halo 2's campaign level Metropolis). After finding different pieces of evidence left behind - a flashback is triggered and the player assumes the role of the missing ODST. 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.

Halo 3 ODST includes a new game mode never before seen in a Halo game, Firefight( much like Gears of War's Horde mode)involves the player defeating countless waves of covenant troops. Each round activates a certain skull which makes the game harder.

Halo 3 ODST also includes Halo 3 Mythic, the second disc of ODST, it includes all of Halo 3's multiplayer maps(original, Heroic, Legendery and Mythic) plus three new maps(Mythic 2)