Metal Gear: Ghost Babel is a 2D stealth action game made by Konami and was released for the Game Boy Color in 2000. Ghost Babel was produced by Konami Computer Entertainment Japan after they were commissioned by Konami's European branch to develop a portable adaptation of Metal Gear Solid. Ghost Babel is not part of the mainline Metal Gear canon, but instead takes place in an alternative continuity set seven years after the events of the original Metal Gear.
Ghost Babel follows the overhead 2D format previously used in Metal Gear 2: Solid Snake while adding a few new elements introduced in Metal Gear Solid. As with previous games in the series, the objective is to infiltrate the enemy's stronghold while avoiding detection from guards or surveillance systems. The player can acquire numerous items and weapons to help them fulfill their mission. One difference from the original games is that the screen now scrolls when Snake moves throughout a single area instead of using flip-screens. Moreover, all the characters in the game now move in eight directions, allowing both the player and the enemies to move diagonally in addition to the four cardinal directions. Snake now has the ability to flatten himself into walls like he does in Metal Gear Solid. By flattening himself, Snake can move across the wall (allowing him access to tight passages that are not accessible by walking), scroll the camera behind his position to scout the area ahead, or knock the wall to lure nearby enemy soldiers. Depending on the difficulty, the number of punches required to defeat an enemy soldier differs and in the higher difficulty levels, the enemy soldiers will be knocked unconscious for a while after the first series of punches instead of simply being defeated. Crawling is now assigned to the Start button (instead of pressing two buttons simultaneously) and the changing of weapons and equipment is done on the main game screen rather than on separate sub-screens. Like in the previous installments, the player communicates with various allies via a wireless communication device (the Codec), which is also used to save the player's progress.
Unlike the preceding installments, Ghost Babel uses a stage-based structure, with a total of 13 stages. After completing a stage, the player's performance is graded from "Terrible" to "Excellent". Much like in the original Metal Gear Solid, the player's overall performance is graded with a codename after completing all 13 stages, with the codenames varying depending on the difficulty level chosen at the start of the game.
Seven years after the Outer Heaven uprising, a new Metal Gear prototype (codenamed Gander) has been stolen by a separatist guerrilla group in the region of Gindra in Central Africa, The Gindra Liberation Front (or GLF), led by the mercenary Augustine Eguabon, plans on using the prototype as a means of achieving victory in an ongoing civil war. Solid Snake, the FOXHOUND operative responsible for the destruction of the original Metal Gear seven years before, is brought back from his retirement in Alaska. His mission is to infiltrate the group's headquarters Galuade, the fortress that was formerly Outer Heaven.
During the course of his mission, Snake teams up with Sgt. Christine Jenner, a surviving member of the Delta Force that was sent before him to retrieve Gander. The GLF are assisted by four surviving members of Black Chamber, a defunct special forces unit whose members are given animal-themed codenames similar to FOXHOUND. They are led by Black Arts Viper, a boobytrap specialist who wields a prosthetic left arm. Joining him are Slasher Hawk, an Australian Aborigine armed with two giant boomerangs who is accompanied in battle by a hawk; Marionette Owl, a former serial killer endowed with owl-like nocturnal vision and attacks with his two bunraku puppets; and Pyro Bison, a pyromaniac armed with a specially prepared flamethrower and fuel pack. As Snake goes deeper into Galuade and confronts each member of Black Chamber, he uncovers a conspiracy involving the GLF and US Government.