Metal Gear: Ghost Babel, retitled Metal Gear Solid in its English localization, is a stealth game that was developed and published by Konami for the Game Boy Color. It was released in Japan in April 2000; the North American release followed in May. This is the only Metal Gear game to get an E rating from the ESRB. The game is part of the Metal Gear series. Although it was released outside of Japan under the title Metal Gear Solid, it is not an adaptation of the PlayStation game of the same name, though the retitling is often viewed as an attempt to make the game more marketable in the western market. While Ghost Babel closely resembles Metal Gear 2: Solid Snake, it also adapts a few gameplay elements introduced in the PlayStation Metal Gear Solid.

The game's storyline is set outside of the main Metal Gear continuity and thus, is non-canonical. While Ghost Babel does not officially follow any of the previously-released Metal Gear titles, it uses the original Metal Gear as a branching point and can be considered as an alternate sequel to it (much like Snake's Revenge on the NES), taking the storyline in a different direction from Metal Gear 2: Solid Snake and Metal Gear Solid. The game features Solid Snake as the main character, along with Roy Campbell and Mei Ling.