Halo 4 will deviate from the original trilogy a bit by focusing on the Forerunners, but Master Chief and Cortana remain central figures in the coming conflict.
Chief will be as we remember him, for the most part, with a few new perks. We saw an instance of his in the Halo 4 CG teaser shown at this year's E3, when Chief uses thrusters on his armor to move through the wreckage of Forward Unto Dawn. For the most part, developer 343 is keeping these new modifications under wraps; according to 343's Frank O'Connor, the changes made to Chief's armor are actually tied to the game's story.
"There's some fairly radical modifications to his armour. Some of those are an artistic evolution, but some are connected to the story. We just can't talk about it yet. He's been in space for a long time."
As most Halo fans already know, advanced AI such as Cortana are prone to rampancy in just seven years, making them unstable and dangerous. Cortana's time draws near, and she was only able to last this long thanks to all the information she was exposed to. Even so, O'Connor mentions the negative effect this could have on her.
"Seven years is the lifespan for a smart AI before it enters a state called rampancy.
"Cortana was getting close to the end of her natural lifespan at the end of Halo 3 but she has been exposed to far more information than any other AI in existence. She's going to develop some muscle from that process but it also contributes to her rampancy - that much information makes things worse."
One of the greatest challenges for the team might be creating something new and refreshing for Halo 4 without completely undoing the previous Halo trilogy. By now, we've certainly grown familiar with Forerunner tech and architecture, but with the focus now falling on this mysterious ancient civilization, 343 must find ways to present them in an exciting light.
In addition to new weapons and vehicles, 343 plans to throw in plenty of new worlds to explore. While the Forerunners were constructing the Halo weapons, they also made Shield Worlds to protect their civilization from the Halos' devastating power. Halo's new art director Kenneth Scott describes the new environments as another "aspect" of the Forerunner architecture from previous games.
"It's a different aspect of Forerunner architecture. The thing that connected people to the first Halo is that mystery, so that's where a lot of our pressure on the art team is going right now. We want the player to feel that initial experience of discovery."
In O'Connor's words, the devs hope to reinstate "the sense of wonder and mystery," hence the return to exploration.