AN  ALTERNATE  SEQUEL   The original title of this game is "Metal Gear Ghost Babel", and it is set outside of the main Metal Gear cannon as an alternate sequel to "Metal Gear".   Having been released between the rave reviews of the critically acclaimed 1998 "Metal Gear Solid" and the highly anticipated 2001 "Metal Gear Solid 2 Sons of Liberty", the game was renamed for marketing purposes in the U.S.   Now released under the title "Metal Gear Solid", it confused many fans that thought it was a port/remake of the PlayStation game onto the Game Boy Color.   To some degree this alienated some fans who didn't see the need to re-play the game in 2D.  Even though it received high praise from the critics, the sales were fairly low.   Some fans confused it for a "Metal Gear Solid" port while others didn't want to have anything to do with a non-cannon title.  Shinta Nojiri was chosen to direct the project and Yoji Shinkawa returned as the art director.  Hideo Kojima wrote the script and was in supervisory control.
The characters are very closely modeled after the cast of "Metal Gear Solid".    Chris Jenner is a mirror image of Meryl Silverburgh, while the Black Chamber unit and its leader Viper are reminiscent of Liquid Snake and Fox-Hound.   Snake even wears the same sneaking suit he does in "Metal Gear Solid".  Basically, this game was designed to be MGS in 2D with a different plot.   The similarities where meant to cash in on the success of the PlayStation blockbuster.  
GAME  DESIGN  The game shares elements from the early MSX2 titles mixed with design elements of "Metal Gear Solid".  The Game Boy Color is by far the weakest system that a Metal Gear game has ever been on; as such the graphics are the simplest of any other title in the series, even the first 2 games.   However, even with its graphic limitations, the game manages to convey some of the MGS gameplay elements.  
"Ghost Babel" plays very similar to other Metal Gear titles with a top-down view of your character.  Unlike the stiff movements in the MSX2 games, Snake runs a bit smoother and also has the ability to move diagonally.   Abilities such as crouching, crawling, tapping objects to make noise, and leaning up against the walls work great even in a 2D environment.   Adding a feature from "Metal Gear Solid", Snake can be leaned against a wall and the screen is shifted a bit to take a peak at what is happening ahead.   Some of these abilities actually make the game more dynamic in gameplay over the MSX2 predecessors.  The equipment and weaponry are very similar to the PlayStation counterpart, minus the Stinger missile launcher.  The cigarettes were replaced with a Fogger due to the Game Boy Color system being considered as children-oriented.  The radar system is present, but is somewhat hard to use given the small size of the screen.   As before the Radio Codec is used to move the plot as well as to Save data and appears the same as it does in "Metal Gear Solid".

GAMING  MODES

There are several game modes present.   The main is the Story Mode, composed of 13 stages.   Once a stage is complete you can go back and replay it for a higher score (faster time, less kills, less alerts, etc).   When the game is cleared once, a Special Mode is unlocked, where the player goes through VR-simulated versions of the main stages with new objectives. By completing these special missions, various facts concerning the events of the game are revealed    Finally, there are 180 VR Missions, modeled very closely after the ones in "Metal Gear Solid".   Finishing all of them will unlock a Sound Mode in Options that enables you to listen to all the games music tracks.       You can play against another player through the link cable.  In the VS. Battle, the player must collect three data disks by defeating certain enemies (called WISPs) and then reach the goal before the other player does. The players are invisible from each other as long as they stay out of their field of vision. If one of the players is killed, then the data disks collected will be lost and they will have to start collecting them again.  This can be considered as the prototype for the Online multi-player mode introduced in "Metal Gear Solid 3 Subsistence" and later on in a portable format with "Metal Gear Solid Portable Ops".  In the Japanese and European releases of the game, the CODEC frequency 140. is included next to Shuyo Murata's entry in the credits.  Calling this channel in-game launches "Idea Spy 2.5", a comical radio play.

NON  CANNON

"Ghost Babel" is not part of the main Metal Gear cannon, despite hardcore fans trying to find ways to include it.  There are several reasons, besides the official word from Kojima, that show it as an alternate sequel to "Metal Gear":

>  The game takes place in 2002, 7 years after Outer Heaven.  Any references to past missions only include the events of "Metal Gear" with nothing said of "Metal Gear 2 Solid Snake". 

>  In discussion about Snake destroying the Metal Gear tank in the past, only the Outer Heaven model is referenced, even though Snake destroyed Metal Gear D in Zanzibar ("Metal Gear 2 Solid Snake").

>  Solid Snake meets Mei Ling for the first time at the start of the mission.   He also meets Mei Ling for the first time in "Metal Gear Solid".

>  The backstory given to the development of Outer Heaven is completely different than the one in the main cannon games.

>  Some felt that the use of the name "Jack" for the operative controlled in the Special Mode stages was in reference to Raiden in "Metal Gear Solid 2 Sons of Liberty" and that "Ghost Babel" was his VR training.   However, this is false.  Solid Snake in "Ghost Babel" knew and referenced the Outer Heaven incident frequently.   Raiden, on the other hand, showed no knowledge of it in MGS2.

Characters

Solid Snake  The "Legend" that took down the military state of Outer Heaven and Big Boss 7 years ago.   Now retired he lives in Alaska.

Roy Campbell  Snake's former commander during his FOX-HOUND days.   He was unknowingly responsible for leading FOX-HOUND when the Black Chamber unit was wiped out. 

Mei Ling  The technical engineer for the mission.   She developed the radio Codec system and the Radar.

Chris Jenner - A surviving member of the Delta Force team that was sent to Galuade before Snake. However, her true objective is to destroy all evidence of John Parker's involvement in Project Babel and to assassinate Eguabon. Her rank was Sergeant.

Ronald Lensenbrink (Weasel) - A mercenary who is said to be Solid Snake's equal, although he does not participate as a field agent in the mission.  Instead, he provides information about Black Chamber and weapon usage to Snake. His true job is to kill Snake's support crew and to prevent them from exposing the truth about Gardner.

Brian McBride - Director of Operations for the CIA, Africa Affairs. He provides geographical and political information about Gindra. After revealing that he is actually a spy and the fifth member of Black Chamber.

James Harks (Jimmy the Wizard) - A teen prodigy who is kept alive by GLF for the purpose of completing Metal Gear. 

Black Arts Viper - The leader of Black Chamber. He specializes in setting boobytraps and illusions. He lost his left arm during the ambush and thus, uses a prosthetic in combat.

Pyro Bison - Black Chamber operative who wields a flamethrower. He has a strong affinity for fire and the fuel in his flamethrower is made by him from a specially-prepared compound.

Marionette Owl - Member of Black Chamber who has nocturnal vision like an owl. He attacks with his two marionettes (Osan and Kohal), created from the limbs of his victims. He was formerly a serial killer.

Slasher Hawk - Aboriginal member of Black Chamber.  He is accompanied in battle by a hawk, a guardian deity in his tribe. He attacks with two giant boomerangs.

General Augustine Eguabon  - The leader of GLF. He was secretly being funded by the Army Chief of Staff John Parker and the U.S. while posing as a rebel leader in Gindra.  He once served as a subordinate of Big Boss in Outer Heaven.

Sophie N'dram - The second-in-command in GLF. She supports Eguabon's cause, unaware of his connections to the U.S.  She's the illegitimate child of a French man and a Boian woman and holds a great resentment to her father for ignoring her and her mother.

Steve Gardner - The National Security Advisor and the mission controller. He funded the development of Metal Gear and Outer Heaven while serving as Deputy Director of Central Intelligence. He resurrected the Metal Gear project as "Project Babel", but lost his position to John Parker. He plans Snake's entire mission in an attempt to tarnish Parker's reputation.  (Does not appear in the game)

John Parker - The Army Chief of Staff. He took over "Project Babel" after Gardner and funded the GLF until the hijack of Metal Gear. He attempts to destroy any evidence that implicate him by sending Chris Jenner.  (Does not appear in the game)