Well, this is the big one, of course...
And ideally, it's the final chapter in the entire saga, and it goes down like this: Kojima keeps making Big Boss games; however many he wants. One more after MGS 5 maybe? Or whatever. But it all builds up to a final game simply called Metal Gear. The story retells the events of MG1 and MG2.
Grizzled, dangerous old Big Boss vs young, Solid Snake in his prime.
BB is commander of Foxhound and sends a rookie codenamed Solid Snake to sneak into Outer Heaven and rescue the MIA Grey Fox. Halfway through the game, Solid discovers the truth, that Outer Heaven is actually led by BB and fights him to a stalemate, BB escapes to Zanzibar Land, and in the second half, Solid is sent to pursue him. His radio contact becomes the newly promoted leader of Foxhound, Roy Campbell. Kaz is in it too.
Big Boss is voiced by Keifer Sutherland. Solid Snake is voiced by David Hayter. Some of the game is played as BB and some as SS.
It culminates with the iconic hand to hand fight between Grey Fox and Solid in the minefield, and is done in some Kojima way that becomes one of the most memorable moments in video game history, like the flowers in MGS3. And so does the fight that comes afterwards, BB vs SS. In the end, Grey Fox is presumed dead, Big Boss is burned up, and Solid Snake disappears. In the final shot, we hear Campbell reporting that he's gone and can't be located, but the visuals show us where he is. In the Alaskan wilderness, he's in a tiny cabin, drinking whiskey as he and all his sled dogs pass out near a space heater as a snowstorm rages outside.
The Best is Yet to Come swells in the background.
The End