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.
Gameplay in the series remains relatively consistent throughout each installment: players assume the role of a starship called the Vic Viper in its efforts to vanquish the Bacterian army before they destroy the planet Gradius.
Common elements throughout the series include enemy "Moai" statues, additional playable ships, and boss rush segments.
These releases contain extra features and bonuses such as enhanced artwork, expanded soundtracks, and story materials.