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.

mGBA is an emulator for running Game Boy Advance games. It aims to be faster
and more accurate than many existing Game Boy Advance emulators, as well as
adding features that other emulators lack. It also supports Game Boy and
Game Boy Color games.

Homepage:
https://docs.libretro.com/library/mgba/
