Metal Gear Ac!d, is a turn-based collectible card tactical game developed by Kojima Productions and published by Konami Computer Entertainment Japan for the PSP. The game was first unveiled at E3 in May 2004, and was released in Japan on December 16, 2004, in North America on March 22, 2005, and in Europe on September 1, 2005. It was the first game in the Metal Gear series for the PSP. Acid focuses on turn-based tactics, using a trading card-based system to control the main character's movements and actions. Acid in the name stands for "Active Command Intelligence Duel". The cards are not truly collectible, as the game is complete with a single purchase. However, the game does feature deck design and deck optimization elements. The game allows for multiplayer gameplay by wireless ad-hoc connections of two PSPs.