Contra (Kontora?), released as both Gryzor and Probotector in Europe and Oceania, is an arcade game released in 1987 by the Konami corporation. The player controls a commando who battles waves of enemies including humanoids, machines, mutants and giant aliens to reach his ultimate goal. Much of the game's popularity came from its two-player simultaneous gameplay, which was an uncommon feature in video games at the time of Contra's release. While successful in the arcades, the game became and remained widely popular and remembered when it was ported to the Nintendo Entertainment System in 1988. Contra was voted #1 by gaming website IGN.com as being the "Toughest Game to Beat" (via)
The player's character is equipped with a rifle with an unlimited amount of ammunition. The player can also jump, move and fire in eight directions. The protagonists can move and jump simultaneously while firing. Coordination of the character's movement is essential, as a single hit from any enemy, bullet, or other hazard will instantly kill the player's character, and also discard the current weapon from the player's inventory. It is not unusual for the screen to be occupied with several enemies and dozens of bullets moving in different directions all at once in the game's eight stages.