Yes, it stars Big Boss.
But, no. It doesn't star Big Boss.
"Ground Zero" for Metal Gear is Outer Heaven. Kojima wants us to make this connection.
The most common usage of the word "zeroes" is "zeroes and ones"; binary code. Binary code is used in computers and shit.
METAL GEAR SOLID: GROUND ZEROES TAKES PLACE INSIDE A COMPUTER
HAVE PLANTED A BOMB
INSIDE THE INTERNET
AND IT IS UP TO RAIDEN TO GET IT OUT
no but seriously
A: Raiden's training for the Big Shell, playing as Big Boss in VR.
B: Snake needing to get Liquid (or Solidus or Ocelot)'s nanomachines out of a computer.
C: A prequel to Snake Eater, with two stories; one for The Boss and one for Snake.
D: Really shitty because it isn't any of these things.
Personally, I'm hoping for B. I miss Liquid.
To be fair, though, I never finished Peace Walker. The boss fights are worse than Human Revolution's.