The codename of Snake's mission (Operation: Intrude N313) is actually an inside joke regarding the development of the game. After
Hideo Kojima's earlier game, "Lost Warld," was cancelled, he was assigned to work on a nearly cancelled military-themed game bearing the working title of "Project N312." Kojima departed from the game's original premise and gradually turned the game into what eventually became Metal Gear. In the game, Grey Fox's failed mission was titled "Operation: Intrude N312."
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