Metroidvania is a subgenre of the action-adventure video game genre which borrows heavily from the general gameplay concepts of the Metroid series and the Castlevania series (specifically from and onward). The genre name is a portmanteau of the two series' names. Other names include "Castletroid", a similar portmanteau, and "Igavania", in reference to Koji Igarashi, a major developer of Symphony of the Night and many other Castlevania games and whose contributions have shaped the design of the subgenre.