Metal Gear Acid is a turn-based collectible card video game developed by Konami Computer Entertainment Japan for the PlayStation Portable handheld game console. The game was first unveiled at E³ 2004 in May, and was released in Japan on December 16, 2004, and in North America on March 22, 2005.
While the Metal Gear series, despite being stealth-based, has always had a heavy influence on action, Metal Gear Acid is not action-oriented but focuses on turn-based strategy (this is why the game's logo lacks the "Tactical Espionage Action" tagline featured on all of the Metal Gear Solid games). It uses a trading card-based system to control the main character's movements and actions. Metal Gear Acid is a "side-story" and not part of the series' main storyline (similar to the earlier Metal Gear: Ghost Babel, and the even earlier Snake's Revenge).
