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. FreeIntv is a libretro emulation core for the Mattel Intellivision designed to be compatible with joypads from the SNES era forward even with software that originally required a number pad.