Gradius Gaiden (グラディウス外伝, Gradiusu Gaiden) is a 1997 horizontal scrolling shooter video game developed and published by Konami for the PlayStation console. The game was released exclusively in Japan on August 28, 1997 and was later re-released on November 20, 2003 as part of the PSone Books collection. Gradius Gaiden didn't see availability outside of Japan until the release of Gradius Collection on the PlayStation Portable, which was released worldwide in 2006.