Gradius is a side scrolling shooter, a spiritual successor to Scramble, and the first in the Gradius franchise. Players control a ship called the Vic Viper through multiple space stages. The enemies encountered include a large array of alien ships and creatures which try to collide into the Vic Viper or shoot it down. Luckily, throughout each stage power-ups are collected by shooting down certain color enemies. Power-ups are saved up on a power meter on the bottom of the player's screen. Once a player reaches the power-up cell that they wish to buy, it can be obtained by pressing the select button (NES release). The power-up cells include:
- Speed Up: Increases the movement speed of the Vic Viper.
- Missile: Drops missiles to kill ground targets with every shot.
- Double: Shoots two cannon shots at once rather than one shot.
- Laser: Replaces the standard cannon shot with a laser beam.
- Option: Creates a hovering orange ball that follows the Vic Viper doubling its firepower with each Option.
- ?: Provides a shield on the front of the ship.
At the end of each stage a boss battle takes place where, more often than not, the Vic Viper must shoot at its core to destroy it. Many of these bosses have shields that protect their core that the player must destroy before being able to lay waste to the core itself.
- The NES version was the first game to ever include the Konami code.