343 Studios is working on more projects than they've already announced, according to a recent blog post.
The Halo 4 developer already revealed they will be heading off Xbox TV programming with a Halo TV show handled by film director Steven Spielberg, and that a Halo is in development for the Xbox One. However, more projects are in the works, according to the Halo Waypoint blog.
"What is looming on the horizon for the studio is both exciting and daunting," 343 writes. "We're working on projects that you know about (the TV show and Halo Xbox One) and others that you don't (insert absolutely zero clues here)."
The Halo trailer shown at this year's E3 was initially thought to be Halo 5, but the number was purposefully left off of the title screen at the end of the trailer.
Microsoft Games Studios vice president Phil Spencer previously told IGN that the E3 trailer wasn't the forthcoming game, and he didn't want to be disingenuous by saying it was. However, he did say that the in-development Halo Xbox One title is coming in 2014.
That same 2014 release date raises the question as to whether a Halo 2 Anniversary game is in development, as next year is Halo 2's 10-year anniversary, and development would presumably need to already be underway to meet that release window.
Source : ign[dot]com