Life Force was developed and published by Konami, originating as the 1986 arcade shoot ’em up Salamander, a spin-off of the studio’s hit Gradius built instead of an immediate direct sequel and released internationally under the Life Force name. Rather than a straight arcade port, Konami used the NES conversion, which reached Japan in 1987 and North America in August 1988, to rework the game’s presentation around an entirely new story about a squadron flying inside a colossal living organism, giving the whole game an organic, biomechanical visual theme distinct from the original Salamander’s more traditional space setting. It kept Salamander’s key innovations over the original Gradius, including a simplified, immediate power-up system instead of Gradius’s segmented meter, full two-player simultaneous co-op, and stages that alternate between horizontal and vertical scrolling rather than staying locked to one direction. Players again pilot the Vic Viper, or a second Lord British ship in co-op, blasting through waves of Bacterion forces and the game’s memorably grotesque organic boss creatures, and the NES version’s distinctive body-horror aesthetic has made it one of the more visually striking shooters in the console’s library.