Set two years after the events of Konami's 1992 SNES shooter Contra III: The Alien Wars, Contra 4 pits Bill Rizer, Lance Bean, Mad Dog, and Scorpion against the vicious Black Viper. Retaining the series' traditional 2D perspective and two player co-op, the game adds new elements to take advantage of the Nintendo DS hardware, such as levels and bosses that span both of the portable's screens and a new grappling hook to aide in the navigation of the taller levels and exploitation of enemy weak points.

While Contra 4 marks the first numbered sequel in Konami's Contra series in over a decade, the franchise has seen a recent surge of activity thanks to the inclusion of the original arcade Contra in Konami's DS compilation Konami Classics Series: Arcade Hits, the release of Contra III: The Alien Wars on Wii Virtual Console earlier this year, and last year's Xbox Live Arcade port of the original arcade Contra by Digital Eclipse. Several non-numbered Contra entries have also been released since Contra III, the latest being Konami's Neo Contra on PlayStation 2, which arrived in 2004.