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. Gearsystem is a cross-platform Sega Master System / Game Gear / SG-1000 emulator written in C++.