Libretro is a simple but powerful development interface that allows for the easy creation of emulators, games and multimedia applications that can plug straight into any libretro-compatible frontend. This development interface is open to others so that they can run these pluggable emulator and game cores also in their own programs or devices. NXEngine is a Cave Story game engine clone developed by Caitlin Shaw. Cave Story is a platform-adventure video game developed over five years by Daisuke "Pixel" Amaya. Cave Story features 2D platform mechanics and is reminiscent of the classic games the developer played in his youth, such as Metroid and Castlevania. It received wide critical acclaim for its compelling characters, setting, story and gameplay.