Halo 3: ODST

The New Bungie Halo Project is the name given to a new Halo game being worked on by Bungie.

Overview
Although Bungie has consistently stated that Halo 3 was the last game in the trilogy, having never ruled out possible Halo games, an interview by MTV with Don Mattrick revealed that Bungie's game is at the very least Halo-related, and that it is not Bungie's collaborative efforts on Halo Wars or Halo: Chronicles, but a "new" game. Although a proper announcement was meant for July 16th, 2008, at E3, it was canceled by Microsoft because they wanted to focus on games by First-Party developers that were coming out in 2008 - criteria which the Bungie project did not fit. The project itself has not been canceled, only the announcement of it. Many people have rumoured that the Game is a tactical squad-based Halo game.

There was also a Wal-Mart stock list that listed a game called Halo: Blue.

It also may have a connection to the Superintendent

Despite the official announcement of the game being canceled, a few seconds long clip can be seen on the following link of an E3 2008 video: http://videogames.yahoo.com/events/playback/playback-5/1231237

It depicts a trio of marines (one possibly being the player due to camera position) driving a warthog through a destroyed human cityscape. This has been confirmed to be the Halo Wars trailer.