Metal Gear 2: Solid Snake is a stealth action game that was written and directed by Hideo Kojima and developed by Konami. It is the second game released in the Metal Gear series and the seventh one chronologically. It was initially released only in Japan for the MSX2 computer on July 20, 1990. The game was re-released as a downloadable game for mobile phones in Japan in 2004. A North American and European version of Metal Gear 2 was released in 2006 as part of Metal Gear Solid 3: Subsistence along with the original Metal Gear. In the game, Solid Snake must infiltrate Zanzibar Land, a heavily defended territory located in Central Asia, to rescue a kidnapped scientist and destroy the revised Metal Gear D. The game significantly evolved the stealth-based gameplay of its predecessor "in almost every way," introduced a complex story line dealing with themes such as the nature of warfare and nuclear proliferation, and is considered "one of the best 8 bit games ever made." However, the game was not released in the Western world, due to the conflicting release of Snake's Revenge, until 16 years later.