The game uses a power-up system called the "power meter", based upon collecting capsules to purchase additional weapons.

", as the standard of boss battles in the Gradius series involved combat with a giant craft, in the center of which would be situated one to several blue colored spheres.

The player must fire shots into this passage while avoiding attack patterns from weapon emplacements on the body of the boss.

When the core has sustained enough hits, it usually changes color from blue to red, indicating that it is in critical condition and its destruction is imminent.

While most arcade games utilize distinct power up-items that each correspond to a specific effect on the player character, Gradius has a single power-up item.

[8] The shoot'em up genre had seen a resurgence at the time with Namco's Xevious, with the goal of the project being to make a shooter that could surpass it.

[8] Development of Gradius lasted for about a year, which Hiroyasu says was filled with anxiety and worry from the production team due to it being their first game, lacking confidence in what they were doing.

[8] While designing the Option satellites, the team tested over 20 different movement patterns for them, which were cut through the process of elimination based on those that didn't work.

[8] Hiroyasu wanted the game to have a visually distinct world with unique enemies and locations, something relatively uncommon for shooters at the time.

[8] The idea for the power meter mechanic stemmed from the team's desire to give players the freedom to select whichever weapons they pleased.

[8] The Moai enemies were added to pay homage to Xevious and its Nazca lines, and as a way to give the game a sense of mystery.

The game was distributed as a standard printed circuit board in North America and Europe under the title of Nemesis.

To balance this, the game spawns a fleet of orange enemies when the player loses a life to provide as many power-up capsules as possible to recover as many upgrades as possible.

[10] Due to the hardware limitations of the Famicom, many of the level designs were simplified (the Moai stage, for example, lacks the vertical scrolling present in the arcade game) and the maximum amount of options that the player can upgrade to was reduced from four to two.

In addition to the MSX, Gradius was also ported to other microcomputers shortly after its release, such as the ZX Spectrum, Amstrad CPC and Commodore 64 in Europe (as Nemesis: The Final Challenge), as well as the PC-8801 and X1 in Japan.

[11][12] It is also included in the Arcade Classics Anniversary Collection released in 2019 by Konami themselves for PlayStation 4, Xbox One, Nintendo Switch and Windows.

[20] IGN gave the Wii Virtual Console re-release a rating 7 out of 10 and has hailed it as one of the greatest classic side-scrolling shooter games.