According to an interview originally published by Electronic Gaming Monthly with the game's producer, Masahiro Hinami, the 'Acid' part of the title actually has three different meanings. The first meaning refers to Acid's departure from the previous Metal Gear games in terms of style, which is an analogue to acid's ability to dissolve metal. The second is a reference to vecuronium bromide, the chemical used by Elsie and Frances to hijack Flight 326. 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.
