Gradius (グラディウス, Guradiusu, /ˈɡræd.i.əs/ GRAD-ee-əss) is a series of shooter (shoot'em up) video games, introduced in 1985, developed and published by Konami for a variety of portable, console and arcade platforms.

During the game, many enemy craft leave behind items or 'pick-ups' when destroyed that can be used to power up or modify the player's vessel.

This innovation allowed for deeper tactics on the part of the player and for greater freedom of weapon choice rather than relying on the pre-determined power-ups common in other games in the genre.

Originally released as an arcade game, its popularity resulted in ports to the ZX Spectrum, Commodore 64, NES/Famicom, MSX, Master System, Sharp X68000, Amstrad CPC and PC Engine.

Unlike Gradius, Salamander uses a more conventional weapons system, with enemies leaving a wide variety of distinct power-ups.

There also exists an arcade game named Life Force that is identical to Salamander released in Japanese arcades the same year, except that a Gradius-style power meter is used instead of conventional power-up items, and the stages were recolored slightly as well as given some voiceovers to make the mission about traveling inside someone's body, rather than through space.

An American release was also made, but it retained the original power-up system of Salamander, though it was renamed as Life Force.

This version was ported to the Sharp X68000 computer under the name Nemesis '90 Kai, with a number of graphical and aural enhancements.

A graphically enhanced version with smooth scrolling appeared in the Japan-exclusive PSP Salamander Portable collection.

The game did not see a North American release until 2006 as part of the PlayStation Portable title Gradius Collection.

The Super Nintendo Entertainment System (SNES)/SFC port includes alterations to levels, enemies, and weapons.

The original arcade version's ending had the main boss in a mechanical setting, then going through a speed-up zone to escape the enemy base, whereas the SNES version had the player simply avoiding the final enemy's simple and slow-moving attack patterns with no challenge afterward.

However, the SNES version introduced the Rotate and Formation Option types, both of which were reused in Gradius V. The difficulty and major boss tactics were toned down to make it easier.

It was one of the larger Game Boy carts in existence at the time (2-Megabits), and was completely different from the rest of the series.

This is also the only Gradius game (other than Gofer no Yabō Episode II on the MSX) where players can select which ship they wish to use.

Gradius Gaiden includes the Lord British Space Destroyer from Salamander and two (relative) newcomers: the Jade Knight and the Falchion β (a variation of the ship from the Famicom Disk System game Falsion).

Solar Assault is an arcade 3D rail shooter in the lines of Star Fox or Panzer Dragoon, with Gradius's settings.

Due to never being ported to any console systems, Solar Assault is a relatively obscure part of the Gradius series.

Graphics are rendered in full 3D, although gameplay is still mostly 2D; some areas change the position and perspective of the camera to emphasize the 3D environment.

In the Japanese first-press limited edition, the game included a book detailing internal design, background, and a road map of the Vic Viper series (i.e., "Vic Viper" is the name of a ship series, rather than a single ship), and pre-ordered North American copies included a DVD detailing the history of the series (including Scramble) and replays of Gradius V. Released only to mobile phones, Gradius NEO features a new storyline, taking place roughly 2000 years after the last Nemesis.

A newer take from Konami on the Gradius spoof, this game features anime girl representations, designed by Mine Yoshizaki, of Vic Viper and Lord British, in a mecha musume-style approach.

Cores are usually blue, glowing masses of energy hidden within large warships and protected by a series of barriers.

In some cases, a core is closed or not vulnerable at the beginning of a battle, only opening or becoming susceptible to attack some moments later by turning blue.

[citation needed] The moai statues of Easter Island (Chile) appear as enemies in several Gradius games.

They are mounted on either side of flat, free-floating platforms and fire a series of colorful rings at the Vic Viper.

The Nintendo Entertainment System port of Gradius represents the first ever use of the Konami Code in a video game.

[8] For the story, Hiroyasu's team was inspired by science fiction movies, with the popular sci-fi films at the time being Star Wars and the anime adaptations of Lensman.

[8] Hideki Kamiya stated in an interview that Gradius is one of the top three key inspirational games from his past.

[9] Several of Gradius' starfighters, Core bosses, and various game elements have been adapted into trading cards as part of Konami's Yu-Gi-Oh!