At the VGAs, they debuted a trailer for a game called The Phantom Pain.
Skip to 10:45.
[spoiler]An obviously made-up studio calling itself
Moby
Game
Studios showed a trailer for a game called Phantom Pain (cf.
this Ground Zeroes image - note also
the logo's hidden message), in which a character not explicitly named Big Boss ("Am I in a dream?") wakes up in a hospital with a prosthetic arm ("phantom pain" is a phenomenon related to missing appendages), while soldiers try to kill everybody inside. He tries to escape alongside somebody with bandages all over his face. The shadowy figure of Colonel Volgin appears to be lurking among the flames. It appeared to have been a dream sequence, not least because of the huge flaming sky whale that devoured a helicopter at some point in it. Also, can you spot the Psycho Mantis hidden
in this screenshot?[/spoiler]
I think we can conclude that Kojima is definitely Up To Something.