"Encounter" is an instrumental theme that is included in the soundtrack for Metal Gear Solid, which was composed and performed by the Konami Computer Entertainment (KCE) Sound Team Japan. It is played during the game's Alert phase, whenever Solid Snake is discovered by enemy soldiers, and during some of the boss battles.
A variation of the theme's beginning is played during completion of the VR missions included in Metal Gear Solid. This variation also plays in Metal Gear: Ghost Babel, upon the completion of both main and VR stages.
An Orchestral version of "Encounter" was played during the extended trailer for the PlayStation 3 and PlayStation 4 exclusive Déjà Vu mission for Metal Gear Solid V: Ground Zeroes. In the actual game, a brief snippit of the original version of "Encounter" will play upon recreating a "scene" from Metal Gear Solid, while the orchestral version from the trailer plays during alert mode in the mission. It is also heard in the Déjà Vu cassette tape titled "Resurgence."
The version from Brawl appears in Super Smash Bros. Ultimate. The Brawl mix was also heard in Solid Snake's debut trailer for Ultimate.