Metal Gear 2: Solid Snake is an overhead action-adventure stealth video game, taglined as a "Tactical Espionage Game", that was originally released by Konami in 1990 for the MSX2 computer standard in Japan. Metal Gear 2 was designed and written by Hideo Kojima, who also designed the MSX2 version of the original Metal Gear. The game is unrelated to Snake's Revenge, a separately developed Metal Gear sequel for the Nintendo Entertainment System that was released during the same year in North America. Metal Gear 2: Solid Snake did not have an official English version until its inclusion as a bonus game (along with the MSX2 version of the original Metal Gear) in Metal Gear Solid 3: Subsistence for PlayStation 2 in 2006, almost 16 years after its original Japanese release.
In the game, Solid Snake must infiltrate a heavily defended territory known as Zanzibar Land to rescue a kidnapped scientist and destroy the revised Metal Gear D. The game significantly evolved the stealth-based game system of its predecessor "in almost every way", introduced a complex storyline dealing with themes such as the nature of warfare and nuclear proliferation, and is considered "one of the best 8 bit games ever made."
A major oil crisis seriously affects the global economy in the late 1990s, with petrol deposits running out faster than previous estimates. Efforts to adopt alternative energy sources or attempts to drill for more oil fails to take up the slack. To counter the problem, Czech scientist Dr. Kio Marv bio-engineers a new species of algae, OILIX, that could produce petroleum-grade hydrocarbons with little expense and effort. He unveils the algae to the World Energy Conference in Prague and was on his way to a demonstration in the United States when he was kidnapped by soldiers from Zanzibarland, a Central Asian country established in 1997 after a successful independence war against the CIS. NATO discovers that Zanzibarland's leaders plan to hold the world hostage by controlling the supply of oil through OILIX and nuclear warheads pillaged from old stockpiles marked for dismantling in light of global efforts toward nuclear disarmament. FOXHOUND's new commander, Roy Campbell, brings Solid Snake out of retirement and sends him to Zanzibarland to rescue Dr. Marv on Christmas Eve 1999.
Over the course of his mission, Snake teams up with Holly White, a CIA operative posing as a journalist, and Gustava Heffner, an StB agent and Dr. Marv's bodyguard. He is also reunited with Dr. Drago Pettrovich Madnar, the Metal Gear inventor from Outer Heaven, who claims to have been once again kidnapped and forced to work on another Metal Gear project (named Metal Gear D) for Zanzibarland, as well as oversee mass-production of smaller, non-nuclear-equipped Metal Gear units. Snake learns from Dr. Madnar that Big Boss, Snake's former superior, survived the events of the first game and now leads Zanzibarland.
Solid Snake, formerly retired FOXHOUND agent and hero of the original Metal Gear returns as the playable character. His new mission is to rescue the kidnapped Czechoslovak biologist Dr. Kio Marv from the forces of Zanzibarland. He is assisted by a radio support crew consisting of:
- Roy Campbell, his new commanding officer
- McDonnell Miller, a survival coach and drill instructor
- George Kasler, a military strategist
- Yozev Norden (renamed Johan Jacobsen in the later revised versions), a wildlife expert
- Holly White, a CIA agent posing as a journalist
- Natasha Marcova (Gustava Heffner in later versions), an StB agent and Dr. Marv's bodyguard
- and Dr. Drago Pettrovich Madnar, the Metal Gear designer from the first game, who was captured along with Dr. Marv
Also appearing in the game are Big Boss, the renegade former commander of FOXHOUND; and Gray Fox ("Grey Fox" in the MSX2 version), who disappeared following the events of the Outer Heaven incident.
The bosses of this installment consist of Black Color (Black Ninja in later versions), an experimental drug-enhanced ninja; Running Man, an agile mercenary; Red Blaster, a grenade throwing expert; Ultra Box (the Four Horsemen in later version), an assassination squad specializing in confined spaces; Predator (Jungle Evil in later versions), a jungle warfare expert; and Night Sight (Night Fright in later versions), an assassin who uses a state of the art stealth suit that renders him invisible to both radar and the human eye.
Metal Gear 2 builds upon the stealth-based game system of its predecessor. As in the original Metal Gear, the player's objective is to infiltrate the enemy's stronghold, while avoiding detection from soldiers, cameras, infrared sensors and other surveillance devices. The biggest change in the game was done to the enemy's abilities. Whereas the guards in the previous game could only see in straight lines, the guards in Metal Gear 2 all have a field of vision of 45 degrees. The guards can also turn their heads left or right to see diagonally and move from one screen to another (instead of remaining stationed in one area). The enemy can also hear any noise made by the player, which usually occurs when the player punches the wall, fires a non-silenced firearm, uses an explosive, or walks over certain types of terrain. If the player is discovered by the enemy, then a counter will be displayed on the upper right side of the screen that will go down after the enemy has lost track of the player. When the counter reaches zero, the alert phase will go off and the game will return to normal.
The player has been given a variety of new maneuvers and tools to help them remain undetected and complete the game. For example, the player can now kneel and crawl in addition to walking, allowing the player to avoid making noise, pick up land mines, and hide under tight spaces such as under desks or inside air ducts. A radar with a 3x3 grid on the upper right of the screen shows the protagonist Solid Snakes current position in the center screen (as a red dot), with enemy soldiers as white dots, allowing the player to determine what's ahead. However, the radar is disabled when the player is in alert phase. The radar can also be used with the mine detector equipped to determine the locations of any placed mines or launch Stinger missiles onto an airborne target. Many of the weapons and equipment from the first game are brought over as well as new items such as robotic mice used to distract enemies, a camouflaged mat and three different types of rations with special attributes each. The player no longer needs to rescue hostages to increase in rank; instead health and carrying capacity is increased each time a boss is defeated.
The transceiver has been greatly revamped from the first game as well. The messages the player receives are now based on their current situation and mission objective, rather than the room they're currently in, making them less fixed and more dynamic. The transceiver now displays Snake's face, as well as the face of the character he's currently communicating with. The player can also talk to children living in the fortress to gain new information; the player is penalized with loss of health if he kills a child.