Game Description:Life Force (a variant of Konami's own Salamander) is a side-chapter in the Gradius shoot-em-up seires, featuring the great Vic Viper as your ship of choice. The clasic Konami shooting gameplay seen in Gradius is expanded here with new vertical levels as well as standard horizontal stages, plus 2-player simultaneous shooting.
Released only in Japan (though it uses the US name for what Salamander was called outside of Japan), Life Force changes the gameplay from Salamander slightly, with graphics edited to simulate a shooting experience inside a human body -- aka a "life force". Stages were renamed for body parts and organs, audio was added for describing the mission to the center of the body, and bosses became diseased interior structures. Interestingly, the Japanese arcade game also used a different structure for powering up weapons to be more like Gradius than Salamander.