It seems that Master Chief’s absence from Microsoft’s latest instalment in the Halo universe has not knocked Halo 3: ODST too badly, with news that the game has already sold 2.5m units worldwide since its release on September 22nd.

That amounts to $125m in revenues, according to USA Today. It also takes sales of Halo video games past the 27m mark to date since the release of the first game, Halo: Combat Evolved, in 2001.

The game currently sits at number six in the ELSPA GfK-ChartTrack All Formats Top 40. It debuted at the top of the listings in its first week of release, and charted in third spot in its second week – thanks mostly to the release of EA’s all-conquering FIFA 10.

“We have a plan [for the Halo franchise] that goes out at least six years,” 343 Industries’ Frank O’Connor stated.

“Eventually, it will become very apparent that there is a plan for the way the canon all ties together and the way the comic books and the novels all tie together.”