Metal Gear Acidメタルギア アシッド (Metaru Gia Ashiddo) (stylized as Metal Gear Ac!d) is a turn-based collectible card[2] tactical RPG video game developed by Konami Computer Entertainment Japan for the PlayStation Portable.

[3] Acid focuses on turn-based tactics, using a trading card-based system to control the main character's movements and actions.

In 2016, a jumbo jet carrying Senator Hach, an important politician and likely future presidential candidate, is hijacked by terrorists.

In exchange for the senator the terrorists demand from the United States government Pythagoras, a research project being conducted in the Moloni Republic in southern Africa.

The Moloni government refuses to cooperate and work with the United States, saying that it doesn't want to interfere in its current affairs.

With no other options and time running out, the US government calls Solid Snake to infiltrate the laboratory, discover the nature of Pythagoras, and to rescue Senator Hach.

The third is stated to be an acronym for Active Command Intelligence Duel, a reference to the game's mixture of turn-based tactics with card-based gameplay.

Metal Gear Acid received somewhat positive reviews from critics, citing the game's unique mechanics and turn-based stealth.

[5] IGN gave it a 6.5/10, calling the game's story "contrived", and referencing the occasionally frustrating gameplay while praising some elements.