Halo 3.5
Bungie's new Halo game has been given the name Halo 3: Recon and is to be released next autumn.
As predicted the game will focus on some futuristic ODST paratroopers and will act as a prequel to Halo 3.
It's not technically a new game though but a standalone expansion pack. Because you're no longer the Master Chief apparently you'll have to be a bit more stealthy than usual.