Complex sentence: He was introduced in the original "Metal Gear" series first as the commanding officer and then arch-nemesis of the player character Solid Snake and later becomes the protagonist of "Metal Gear Solid" prequels where he is depicted as an American covert operative.
Split into simpler sentences: He was introduced in the original "Metal Gear" series first as the commanding officer and then arch-nemesis of the player character Solid Snake. Later, he has become the protagonist of "Metal Gear Solid" prequels where he is depicted as an American covert operative.