In Metal Gear Solid 4: Guns of the Patriots, Solid Snake is commonly known as Old Snake.
The nickname reflects Snake’s accelerated aging and his visibly older appearance. Metal Gear Solid 4 is set several years after Metal Gear Solid 2, and Snake’s body has deteriorated because he is a cloned soldier engineered with a shortened lifespan.
The game follows Old Snake as he undertakes a final series of missions against Liquid Ocelot and the systems controlled by the Patriots. His age is not merely a cosmetic change; it affects the story’s themes of mortality, legacy, and the end of an era.
Old Snake is a nickname rather than a separate identity. He remains Solid Snake, the same character who led the Shadow Moses operation in the original Metal Gear Solid.