The arcade game was a commercial success worldwide, becoming one of the top four highest-grossing dedicated arcade games of 1987 in the United States. The NES version was also a critical and commercial success, with Electronic Gaming Monthly awarding it for being the Best Action Game of 1988. Several Contra sequels were produced following the original game.
Contra employs a variety of playing perspectives, which include a standard side view, a pseudo-3D view (in which the player proceeds by shooting and moving towards the background, in addition to left or right) and a fixed screen format (in which the player has their gun aimed upwards by default). Up to two people can play simultaneously, with one player as Bill (the blond-haired commando wearing a white tank top and blue bandana), and the other player as Lance (the shirtless dark-haired commando with a red bandana). The controls consists of an eight-way joystick and two action buttons for shooting (left) and jumping (right). When one of the protagonists jumps, he curls into a somersault instead of doing a conventional jump like in other games. The joystick controls not only the player's movement while running and jumping, but also his aiming. During side view stages, the player can shoot leftward, rightward or upward while standing, as well as horizontally and diagonally while running. The player can also shoot in any of eight directions, including downwards, while jumping. Pressing the joystick downwards while standing will cause the character to lie down on his stomach, allowing him to avoid enemy fire and shoot low targets. When the jump button is pressed while crouching on a higher platform, the character will drop down to a lower level.
Contra is set in the distant future of the year 2633 A.D., when the evil Red Falcon Organization have set a base on the fictional Galuga archipelago near New Zealand in a plot to wipe out humanity. Two commandos, Bill Rizer and Lance Bean of the Earth Marine Corp's Contra unit (an elite group of soldiers specializing in guerrilla warfare), are sent to the island to destroy the enemy forces and uncover the true nature of the alien entity controlling them. The promotional materials for the US arcade version downplays the futuristic setting of the game, with the manual for the later NES and home computer versions changing the game's setting from the future to the present day and the location from Galuga to the Amazon Jungle.