Arcade ports were another staple of the NES library, especially in the early days of the system.
Gradius was released in 1986 by Konami. It came in the same silver box as all the other releases. Pretty much being a straight up arcade conversion for the home consoles and computers. Gradius on NES kept that insane arcade difficulty that kept swallowing quarters in the arcade.
Gradius put players in the cockpit of Vic Viper. Early on, your ship is weak and useless against the onslaught of alien invaders. However, with upgrades, you are unstoppable. It spawned a series of sequels ad spin offs.