Code Name: Viper (JP: Ningen Heiki Dead Fox, or "Human Weapon Dead Fox") is an action game for NES that follows Viper, an agent of the 98th Special Forces, as he rescues fellow commandos from various South American drug syndicate hideouts.
The game was co-developed by Arc System Works, which had ported Namco's structurally-similar arcade game Rolling Thunder to the NES the previous year.
Commander Jones is briefing Mr. Smith about seven hideouts of the huge drug syndicates in South America have been discovered, and that the mission is to destroy them all. One of the commandos has been hurt and captured in one of these seven hideouts, Smith will also have to rescue him and retrieve the grenades that the commando has on him.
Each stage follows a set loop: Viper must first locate the missing commando, who is behind one of several revolving doors (others either contain bonus hostages, extra ammo, or nothing) throughout the level. After procuring the grenades, Viper can then destroy the central command center of the hideout and obtain part of a larger secret missive from the rescued commando. After the message has been fully completed, Viper discovers who the drug cartel's mastermind is and travels to their mansion to defeat them.