The NES version of Metal Gear. It differs from the original MSX2 release in level layout and enemy differences, including an alternative final boss.
The game revolves around Solid Snake, an operative of the special forces unit FOXHOUND, who goes on a solo infiltration mission into the fortified state of Outer Heaven to destroy "Metal Gear", a bipedal walking tank capable of launching nuclear missiles from anywhere in the world, as well as rescue a number of fellow agents who have been captured by the enemy.
This version was later released inside the Metal Gear Solid: The Twin Snakes - Special Disc, along with other extras.