The series debuted in February 1987 with the Japanese coin-operated arcade game of the same name, which has since spawned several sequels produced for various platforms.

[1] The majority of the Contra games are side-scrolling shoot-'em-ups where the player takes control of an armed commando who must fight all sorts of extraterrestrial monsters and other kinds of futuristic menaces.

As software emulation became more widespread, the games would be re-released in numerous formats on several platforms, most notable through the Wii's Virtual Console, the Xbox Live Arcade, and the PlayStation Network.

They are members of a special guerrilla task force codenamed "Contra", who are sent to thwart armies of alien invaders seeking to destroy the Earth.

Yamamoto would also reveal the reason why the game doesn't use the Contra name in its title was due to how "different" fans regarded Hard Corps from the rest of the series.

[2]: 37 Bill would not return until 2002's Contra: Shattered Soldier; where he became a convicted war criminal sent to fight against his former partner, Lance, who has become a terrorist leader.

However, "Mad Dog" and "Scorpion", originally the nicknames given to Bill and Lance in the NES versions of Contra and Super C, were made into separate characters.

The game's main antagonist, "Black Viper", is also treated as a new character, despite originally appearing in the North American version of Operation C (which also refers to protagonist Lance as "Scorpion").

[26] Contra III: The Alien Wars retains its futuristic setting of 2636 for its American release, but the identities of the two player characters, Bill Rizer and Lance Bean (the heroes from the previous installments), were changed to their descendants "Jimbo" and "Sully" in order to retain the continuity of the previous localizations.

[30] The American Super C instruction manual also illustrates a common "running" alien enemy from its final stage as Red Falcon.

In the Japanese version of Operation C, the antagonist was originally a nameless hostile nation seeking to develop alien-based weapons.

Contra Force is a standalone entry that, due to it being originally intended to be separate game altogether, is considered to be non-canon from the rest of the franchise.

[31][32][33][34] Contra ReBirth begins in 2633, but the game's plot primarily takes place in 1973 and incorporates elements of time travel.

This was presumably done due to the German Federal Agency BPjM, which prohibited the sale and advertisement of media deemed too violent to children, including "content which glorifies war".