Gradius is a series of horizontally scrolling shooter video games developed and owned by Konami. The series debuted in arcades with Gradius in March 1985, renamed Nemesis for international versions. Games in the series have been released for several platforms, including arcade hardware, home video game consoles, handheld systems and mobile phones. The Gradius franchise consists of 16 games, including spin-offs, home conversions and compilations, as well as other forms of media such as toys, manga, soundtrack albums and literature. The series has been seen by critics as important and influential for the shoot'em up genre, inspiring games such as R-Type, Thunder Force and Darius, as well as setting the template for horizontal-scrolling shooters as a whole. It is Konami's most successful shooter series and one of the company's core franchises.
The Gradius games have spawned a number of sequels. Being a prominent series in the shoot 'em up genre, the titles have become classics and thus have been repackaged and rebundled in several versions. These releases contain extra features and bonuses such as enhanced artwork, expanded soundtracks, and story materials.