In the past of Metal Gear

(Metal Gear / Release: 1987)

A powerfully armed nation called "Outer Heaven" is suddenly born deep in the jungles of southern Africa. NATO soon learns that they are at work designing a nuclear-equipped walking battle tank called "Metal Gear", and they send in one of their best agents, Gray Fox. However, after Grey Fox is taken hostage, they are forced to send in the newest member of Fox Hound, Solid Snake. Snake is successful. He rescues Gray Fox and forces the surrender of Outer Heaven. But just as he is planning his escape, he sees one man standing in his way. It's the commander of Fox Hound, Big Boss! As it turns out, Outer Heaven is a large scale mercenary company and Big Boss was the mastermind behind all of it. Big Boss had intentionally chose his most inexperienced agent, Solid Snake, in order to spread disinformation to the West, but he seriously miscalculated. "You've gone too far! Too far!" Big Boss shouts with rage at the man who undid all of his carefully laid plans. After a fierce battle in which Big Boss is defeated, Snake emerges victorious as Outer Heaven burns around him.

Uprising of Zanzibar

(Metal Gear 2: Solid Snake / Release 1990)

Dr. Kio Marv, inventor of the oil refining microbe, OILIX, was taken hostage by Zanzibar, a heavily armed nation in central Asia ruled by a minority ethnic group. Zanzibar was planning to gain political and military hegemony over a world suffering under the cruel weight of a worldwide energy crisis. Roy Campbell, commander of FOXHOUND, called Solid Snake, now in retirement, back to active duty to infiltrate Zanzibar and recover Professor Marv.
Solid Snake made it past Zanzibar's impressive steel wall and penetrated deep into its interior. There he once again destroyed Metal Gear, which had been completed after being transported from Outer Heaven, and defeated Gray Fox, former member of Fox Hound and now leader of the Zanzibar mercenary corps. He was also successful in retrieving the OILIX manufacturing process. Finally, he came face to face with the man who was pulling the strings in Zanzibar, Big Boss! He had survived Outer Heaven and created Zanzibar in order to make a world rife with conflict and war, a world in which soldiers such as himself would always have a place. After defeating Big Boss for the second and final time, Snake gave up on war and retired to the peaceful Alaskan wilderness.