Metal Gear Acid

Metal Gear Acid is a turn-based collectible card game and the first Metal Gear series title released for PSP. A Java ME mobile-phone version, Metal Gear Acid Mobile, was released by Glu Mobile in 2008. Metal Gear Acid focuses on turn-based tactics, using a trading card-based system to control the main character's movement and actions. Its title stands for "Active Command Intelligence Duel." The cards are not truly collectible, as the complete game is available through a single purchase, but it includes deck-building and deck-optimization elements. Multiplayer is supported through a wireless ad-hoc connection between two PSP systems. Before each round, players can customize the card deck used by the main characters. Most cards draw on elements from across the Metal Gear series, including weapons, characters, and Metal Gear itself. At the start of a game, a player's hand can hold up to six cards, while the maximum deck size increases as overall progress is made. In action mode, cards can be used for their intended effects or to move the character. Most cards allow movement of three spaces, while some allow movement of six or more. Cost is a central gameplay mechanic that represents the weight of a player's action. With some exceptions, every card has a cost that transfers to the player when it is used. Costs vary significantly between cards: the higher a character's cost, the longer that character must wait for their next turn. For example, if a player character has a cost of 15 and a guard has a cost of 10, the guard takes their turn first. Some cards can be equipped. Weapon cards can have other cards attached to improve their performance, and firing a weapon requires another equipped weapon card that uses the same ammunition type. Some weapons can be used without being equipped, but are discarded afterward. Equipment cards and action cards can also be equipped. Multiplayer, called "Link Battle," lets two PSP systems running Metal Gear Acid connect wirelessly for a "sneak-off." The objective is to collect several diskettes before the opposing player. Because players can steal diskettes from one another, avoiding detection is essential.

In 2016, terrorists hijack a jumbo jet carrying Senator Hach, a prominent politician and likely future presidential candidate. In exchange for the senator, they demand that the United States government hand over Pythagoras, a research project underway in the Moloni Republic in southern Africa. The US government launches an investigation into Pythagoras to identify the terrorists. The Moloni government refuses to cooperate with the United States, stating that it does not want outside interference in its current affairs. The US responds by sending a covert special forces team to investigate, but armed resistance destroys the team. With time running out and no other options, the US government calls on Solid Snake to infiltrate the laboratory, uncover the nature of Pythagoras, and rescue Senator Hach.